These are Windows 7 forums, not 10.

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Reinstall the operating system.

During that process you can delete the existing 7 partition and make a new partition to reinstall it on.

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Or if you just want to wipe everything from the Hard Drive, including the operating system:

Use this: Data Removal: Darik's Boot and Nuke - DBAN

How to Erase a Hard Drive Using DBAN

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OR:

If it came preinstalled:

Here are the Key/s to press at Boot to reinstall the operating system (new condition). Under each Manufacturer in the list below are the instructions in the respective links for you to follow on how to use their Recovery Partition

Acer – Press Left Alt + F10 Keys.

http://acer.custhelp.com/app/answers/detail/a_id/2631

Advent – Tap F10 until Starting System Recovery appears

https://answers.yahoo.com/question/index?qid=20081221054701AAJT8YV

Asus – Press F9

http://support.asus.com/Troubleshooting/detail.aspx?SLanguage=en&m=X53E&os=&no=1775

Dell – Press F8 which will bring up Advanced Boot Options

How to restore a Windows 7 Factory Image on your Dell PC | Dell US

Dell Alienware:

What is and How to use AlienRespawn

eMachines: Press Left Alt Key + F10

http://techchannel.radioshack.com/emachines-system-recovery-1747.html

Fujitsu – Press F8

https://forum.ts.fujitsu.com/forum/viewtopic.php?f=64&t=39428

http://support.ts.fujitsu.com/WDB/FAQContentstart.asp?ID=233412526&WDBStatID=&INFO=SA&quest=&Sprache=en&SprachID=&SecID=&lng=COM&Todo=FAQ

Gateway: Press Alt + F10 Keys - As Acer owns them: press Left Alt + F10 Keys as per Acer eRecovery

http://www.ehow.com/how_6960920_restore-computer-using-recovery-partitiion.html

HP – Press F11 repeatedly

http://support.hp.com/us-en/document/c01867418#AbT3

Lenovo – Press F11

http://support.lenovo.com/en_US/detail.page?LegacyDocID=MIGR-4M7HWZ

LG – Press F11

https://answers.yahoo.com/question/index?qid=20090304161820AAiyvMn

Packard Bell: Press and hold the ALT key while pressing repeatedly the F10 key. Release the keys when a message displays that Windows is loading files.

http://packard-bell-scandic.custhelp.com/app/answers/detail/a_id/3068/session/L2F2LzEvdGltZS8xNDA2MjgyMjczL3NpZC90Z205SDktbA%3D%3D/~/use-packard-bell-recovery-management-to-restore-your-system-or-create-recovery

Samsung – Press F4

http://www.samsung.com/us/support/howtoguide/N0000137/6375/93514

Sony Vaio – Tap F10 until the Edit Boot Options screen is displayed

https://ca.en.kb.sony.com/app/answers/detail/a_id/35585/p/48903,49902,71663,71664/c/65,67/kw/recovery%20using%20f10

Toshiba – Press 0 (zero)

http://forums.toshiba.com/t5/System-Recovery-and-Recovery/How-To-Perform-system-recovery-Windows-7/ta-p/279643

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And if you do have a Manufacturer's Recovery Partition on your Hard Drive and you can Boot into Windows, you should be able to make and have your own Recovery Disks from it to reinstall the Operating System in case of Hard Drive failure.

Look under Programs > your Computer Manufacturer's name > then their System Tools or Recovery Software Headings for them, depending how it is worded.

If you can not find any reference to it, contact the Manufacturer for advice on how to make those Recovery Disks.

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You can borrow the exact same edition of Windows 7 Retail DVD and use your Product Key on the COA sticker to reinstall the operating system.

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Or you can use this for preinstalled OEM or Retail Licenses. This is on a first come, first served monthly basis.

Download the correct ISO file and make your own disk and use the Product Key that is on the COA Sticker. This is on a first come, first served weekly basis.

https://www.heidoc.net/joomla/technology-science/microsoft/67-microsoft-windows-and-office-iso-download-tool

Download: Windows ISO Downloader.exe

And here are instructions on how to burn ISO images to disk:

http://www.snapfiles.com/get/ISORecorder.html

You change the Boot Order in the BIOS to be able to boot from your installation media:

How to Boot Your Computer From a Disc or USB Drive

How to access Boot Menu:

https://neosmart.net/wiki/boot-usb-drive/

Then do a clean install:

http://www.sevenforums.com/tutorials/1649-clean-install-windows-7-a.html

The COA sticker is either on the underside of the Laptop or in the Battery Compartment.

With a Desktop it is either on the side, rear or top of the Computer Case.

Using the downloaded ISO file Method may require phone Activation.

It may require that you use phone Activation.

"How to Activate Windows 7 by Phone"

http://www.sevenforums.com/tutorials/18715-activate-windows-7-phone.html

The above method also will require you to go to your Computer Manufacturer's website > Support and Downloads Section > locate your Model Number and Operating System > then download and install the latest Drivers for it.

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Using the USB method in conjunction with the above Windows 7 download:

http://www.sevenforums.com/tutorials/2432-usb-windows-7-installation-key-drive-create.html

"How to Get and Use the Windows 7 USB/DVD Download Tool"

http://www.sevenforums.com/tutorials/31541-windows-7-usb-dvd-download-tool.html

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And this is very good and easy to use:

Rufus - Create bootable USB drives the easy way

Cheers.