Summary
Windows 10 supports a “Rollback” feature that allows you to go back (recover) to the version of Windows (Windows 8.1 or Windows 7) installed on your PC prior to upgrading to Windows 10.
Note: Originally the Rollback feature was available for 30 days from the time you upgraded, recent changes have reduced this down to only 10 days. After which you will no longer be able to go back to your previous version of Windows!
Details
If you were running any version of Windows 8.1 then you can use this option to uninstall Windows 10 and restore Windows 8.1 without losing your applications, documents, photos and other personal files.
Note: Applications you installed and personal settings changes made while using Windows 10 will not be saved, however existing applications installed within Windows 8.1 and any newly created Windows 10 documents, photos and other personal files will be migrated back to Windows 8.1.
Let’s Start:
You have three easy ways to access the ‘Recovery’ option:
Option #1) Click on Settings > Update & security.
Option #2) In the ‘Search’ box enter: recovery options
Then click on ‘Recovery Options’ displayed at the top of the list.
Now click on the ‘Get started’ button in the ‘Go back to Windows 8.1’ option to start the recovery process.
Note: If you see the following error message: “We’re sorry, but you can’t go back”, skip to the last part of this Wiki article for more information.
Select the option that best describes why you are going back. The text box at the bottom is optional, but can provide useful information to Microsoft as to why you don’t want to continue using Windows 10. Click the ‘Next’ button to continue.
Read the fine print and if you still want to recover / rollback then click on the ‘Go back’ button.
Click on the ‘Go Back to Windows …’ button to start the actual recovery / roll back process.
Option 3) You “may” also have a third method to rollback which is to click on the ‘Windows Rollback’ option displayed on the ‘Choose an operating System’ screen when you power on your PC or ‘Restart’ your PC.
Note: You may need to hold down the Shift key and click on the 'Restart' option from within Windows 10 to see this option.
When you upgraded from Windows 8.1, you should see the following two options when you boot / turn on the computer. Click on the Windows Rollback option to start the process of recovering Windows 8.1.
Now sit back and watch the action.
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You receive the following error message when you click on the ‘Get started’ button:
“We’re sorry, but you can’t go back”
This error is the result of deleting the C:\Windows.old folder.
How did this folder get deleted?
A) You deleted the folder using Windows File Explorer. Typically this file is deleted because of the large amount of disk space it can consume as it contains the entire contents of your previous version of Windows or an earlier build.
Example:
Depending on the size of your disk drive you may find that after installing the Windows 10 Technical Preview there is not much free space on your drive, therefor in an attempt to gain more free space the user deletes the C:\Windows.old folder and or the C:\$Windows~BT folder.
More than likely the file will be too large to be contained in the Recycle Bin but you can always check if it’s there and if so restore it.
B) You ran Disk Cleanup and selected/clicked on the ‘Clean up system files’.
Additional Wiki articles you may want to read:
Windows 10 - What type of product key do I have?
How to get the Windows 10 Free upgrade has been made even easier
Threshold 2 Update - Still waiting for the update, how to get it installed now
Windows 10 Fall Update Threshold 2 now available
How to extend the 30 day limit to go back to your previous version of Windows
