Why would you need a product key? Once you have installed it you can reinstall it at anytime for the life of your device. You can reinstall from an iso file or from the website at

http://www.microsoft.com/en-us/software-download/windows10

And what was the point of creating all those partitions?

I didn't create them. Windows 10 did. And if I erase the hard drive and remove all those partitions there will be nothing left of windows 10. That link definitely states I will NEED a product key since technically I would be installing on a cleaned hard drive that has nothing on it, not upgrading.

Yes, I know. But that applies only to the FIRST installation of 10. You CAN do a Clean Install once you installed it since it is tied to your Microsoft Account. When it asks for a Product Key you just skip that, You do not enter ANYTHING. NO KEY. Once you sign in after the installation it will activate based on your Account Info.

But see this article by Greg Carmack (he's great on stuff like this):

http://answers.microsoft.com/en-us/windows/forum/windows_10-windows_install/how-to-clean-reinstall-windows-10/11ccc09e-eefa-4bcc-80d9-d3d0d249587d

What you CANNOT do is wipe your hard drive BEFORE you install Windows 10 THE FIRST TIME because that IS tied to your previous activated Windows Edition.

Personally I'd use the iso method.

I was not aware that you could simply install with the ISO and not need a product key. The links I have seen on here with asking say that a product key is needed, except the last one from Greg Carmack. I was not spreading any false information. I WAS searching for the answer like a lot of other people.

Hey Mustang -

You can  Create Windows 10 Installation Media to do a Clean Install Windows 10

once activation is confirmed at Settings>Updates and Security>Activation. 

To get it cleanest be sure to delete all partitions during the booted install, using the Drive Options link on the "Where do you want to install Windows?" screen.  Delete it all down to Unallocated Space and then click Next to let the installer create and format your partitions needed and begin install. 

Look over the steps for Clean Install Windows 10 and feel free to ask back as many questions as you need to get them done.  I'll help you as much as you need. 

I was not aware that you could simply install with the ISO and not need a product key. The links I have seen on here with asking say that a product key is needed, except the last one from Greg Carmack. I was not spreading any false information. I WAS searching for the answer like a lot of other people.

Didn't say you were spreading anything, man. Just filling you in on the news.

Remember:

"You're in Good Hands with Carmack" .

I'm off...all your issues should be resolved soon with his help.

My work here is done.

"Hi yo Silver Websurfer, Awaaay!"

My first attempt at upgrading to Windows 10 & performing a clean install the first time went very poorly.  Fortunately for me I chose one of my least important netbooks to experiment with Windows 10. 

(Most of my experience & habits were developed over lots of clean installs of XP & fewer factory resets of Windows 7.  These always fixed any problems that had developed over time.  After getting tired of all the extra work that I constantly had to move, backup transfer etc. I developed the philosophy of creating another partition on my hard drive where I store all of my Documents - I used EaseUS Partition Master, Free.  I personally made this documents partition about 75% of the total capacity of the hard drive while leaving the first 25% for the OS - 80GB max.  Then I move all my documents to the Documents partition.  All XP clean installs & my Factory Resets of Windows 7 only affect the partition that holds the OS thus keeping the documents on the other partition always kept them safe from deletion & saved tons of time once the new install / reset was complete.  The final step I'd developed on previous windows versions is after the Clean install / factory reset is complete is to locate the Documents folder in the default OS folder on the OS partition & through the Properties of the folder Location tab move the folders to the Documents partition.  Since before wiping out the OS partition I had already moved all the documents to the Documents partition I can simply tell the Windows to use my old folder for all the Documents.  In XP I only had to do this with one folder.  In Windows 7 they started using multiple folders, thus it is a bit more laborious, but the same results could always be achieved if I did the same process to each of the Download, Contacts, Music, Video, etc. folders immediately after the fresh install / reset was complete.  If I moved the documents immediately this redirection on the new OS was nearly instant since the fresh install document folders were empty.  If I waited and created a bunch of new files before moving to my documents to the Documents partition I'd have to wait for all the new files to be physically moved.  Once I'd told window to use the existing documents folder on the Documents partition I had access to all my pre Clean Install / Factory Reset documents.)

I said all the above to say as my personal background and for a basis for some of my comments later regarding my attempt at a clean install of Windows 10 the first time.  What happened when I chose not to keep all the old applications & folders etc. on my first attempt to install Windows 10 was that the Install process not only wiped my OS partition, but it wiped my Factory Reset & boot partition of my original Windows 7 making it impossible for me to go back to Windows 7.  The other thing I found is Windows 10 would not accept my Windows 7 drivers from the netbook manufacturer on their website.  The manufacturer only offered Windows 7 drivers so I could not install Drivers to be able to turn on WiFi radio etc. from buttons, etc.  This was unacceptable.  It was at that point I thought there was no need to panic, I could do a factory reset.  That was when I learned the boot partition had been altered & no longer gave me the F2, F8, F10, etc. option to go into Boot Recovery & Install Windows 7 via the Factory Recovery.  So whether it wiped the Recovery partition or not was irrelevant since I no longer had access to to it in while the computer was booting up.  I was fortunate that I had 3 identical netbooks & through trial & error was able to copy my Factory Recovery & Boot partitions from one of my other identical netbooks over to the Windows 10 / messed up netbook & then Factory Reset it to Windows 7 so that all the hardware would have drivers.  After that I was able to successfully Upgrade to Windows 10 by choosing to keep all my applications & folders the 2nd time around.  If I personally did not have access to an identical windows 7 netbook, the Clean Install to my netbook would have made my netbook nearly useless, since things like WiFi are necessary for daily use.

This is shared as, for whatever it is worth information about my experiences on some of the topics being discussed on this thread lately. 

Up until Windows 10 I have always highly recommend my method of moving Documents to a 2nd partition for the fastest access to all the info after a clean install or Factory Reset.  However I can't say from experience whether Windows 10 will allow you to keep them safe on a 2nd partition safely or not.  I never dreamed the Clean Install would touch my Factory Recovery & Boot partition, but it did on my machine so I can't say yet from personal experience that it worked for me even once.  In my experience which shared above, I never got that the machine hardware working properly after the Windows 10 Clean Install so I never event checked the Documents Partition since, like I said, I had no critical Data to even be concerned to look for them.  Until I buy a new machine I won't be brave enough to even attempt another Clean Install again.  I will wait until I have a machine with a Windows 10 Factory Recovery partition.

For me the Clean Install was not a good option & I was fortunate I had the option to experiment with the new OS on a machine that contained no critical Document data as well as an identical machine that save my butt.  After over 24+ hrs. of my personal labor I saved it.  Who knows if I could have even paid a computer shop to solve this for me without the identical netbook to the original Windows 7 Factory Recovery & boot files. 

Good luck to all others debating these topics.  The Cloud backup method mentioned by someone on this thread maybe the safest, but it is likely the very slowest method to be able to replace valuable files should they ever be lost in a Clean Install if a 2nd partition can't keep them safe from the newer Windows 10 Clean Install procedures.

Yes. Well, I can tell you where you screwed up if you'd like to know.

The First Installation of Windows 10 cannot be a Clean Install. It has to be installed via your current Operating System and it has to be able to verify that you have an authorized copy of that Operating System. Only then will it permanently  authenticate your Windows 10 installation.

I don't care how many times you have installed new operating systems over old ones. The instructions on Windows 10 were clear and you paid no attention and just went ahead and did it YOUR way.

Next time maybe you'll follow the instructions.

AFTER your download and activation of Windows 10 was registered you could have done a clean installation without problems. NOT BEFORE.

Thanks for your post, though, you'll serve as a cautionary tale to those who come after you on the dangers of thinking you "know it all".

Did you follow the steps in Clean Install Windows 10  for how drivers are best handled in a driver-complete OS since XP?  I've never seen a driver not be found following those steps. In the rarest case we can help you find one that works - if necessary in Compatibility Mode .

 The data partition loss you bring up seems to pertain more to Factory Recovery, Upgrade or Reset Saving Nothing since it's not possible to delete a data partition doing a Clean Install unless you do it yourself. Whichever of these you used, data should always be backed up externally because the hard drive could die at any time.  

If you do a Custom Clean Install Windows 10 correctly from the booted installation media, you'll always have the choice which partitions to save or delete at the "Where do you want to install Windows?" screen. 

For example in the above screenshot which pictures a typical modern UEFI install, to get it cleanest I would delete all partitions one-by-one until its all Unallocated Space, then click Next to let the installer auto-format partitions needed and begin install.  This avoids confusion when the installer manually creates necessary System partitions in addition to a New C. 

However if there is a Data partition, label it that way first in its Properties so that it's clear by name and size which it is so it can be preserved.  In that case you can delete all other partitions except Data, then in the Unallocated Space click Next to have the System and C partitions auto-create and -format to begin install.  Data won't be touched. 

Again, my suggestion to always get it cleanest is to delete all partitions, however if you know you have a data partition or know for sure Factory Recovery will still run after reinstall (as on HP's which can offer a Minimal Recovery nearly as good as a Clean Install) or that OEM tools will still boot diagnostics (as on Dell) then you can leave those partitions if you think you might ever want the Factory Install or the more valuable onboard diagnostics.  You can also manually Boot Recovery Partition using EasyBCD.  A better way to handle Factory Recovery back-up however is to make the Recovery media so you can then delete its partition.

As it details in Clean Install Windows 10 moving User folders to a Data partition is a popular modern way to keep the C image smaller so  in case Windows becomes irreparable you can restore it from a stored System Image Backup  in 20 minutes and your files are still safe, current and waiting in their own Data partition.  The only way this partition would be deleted is if you choose to delete it at the Drive Selection screen, apply the image to wrong partition, or run a Reset or Factory Recovery which doesn't provide for saving anything in its options offered. 

Incidentally, all of the practices discussed in Clean Install Windows 10 are adapted from my web tutorial to Clean Reinstall Windows 7 which has been used by over 1.7 million consumers without a single complaint.  If there were pathological problems with the Clean Install we would have heard about it by now, but instead all we ever hear is how happy consumers are having the best install in the world, and how convenient the suggested tools and methods are.  This completely changed the industry's view of these as sketchy, and OEM's from forbidding them, to where in WIndows 10 now you can get a clean install of Factory OEM by doing a Reset Saving Nothing.