Hi Seema,

Windows.old folder is created when you upgrade from one version of Windows to another, starting with Windows Vista. The Windows.old folder actually contains all the files and data from your previous Windows installation. It can be used to restore your system to the old version of Windows if you don’t like the new version.
Essentially, the Windows.old folder just contains the old Windows system. From the Windows system files to your installed programs and each user account’s settings and files.

If you have installed Windows 10, then this folder got created after you downgraded to Windows 7 by going to Settings app ->Update & security, and -> Recovery. Then "Go back to Windows 7” or “Go back to Windows 8.1”, depending on which version of Windows you had installed before you upgraded.

If you need to recover individual files from your old Windows installation, you can recover them from the Windows.old folder. This should just be a matter of opening the File Explorer window, accessing the Windows.old folder at C:\Windows.old, and browsing your file system. Your personal files will be located under C:\Windows.old\Users\NAME.


The Windows.old folder can take up quite a bit of space. It might be 12 GB or so of hard disk space.

If you try to delete the Windows.old folder from File Explorer like you would any other folder and you’ll receive an error message. You could potentially bypass this error message by modifying with the Windows.old folder’s permissions.

To delete this folder, use the Windows Disk Cleanup tool. On Windows 7, click the Start button, search for “Disk cleanup” in the Start menu, and launch the Disk cleanup application.
You can also right-click the C:\ drive in File Explorer, select Properties, and click the “Disk Clean-up” button under the General tab.

1. Click the “Clean up system files” button. 
2. You’ll see “Previous Windows installation(s)” appear in the list, and Disk Cleanup will tell you how much space those files are taking up.
3. Check that option and use Disk Cleanup to wipe the previous Windows system files away. You can also use this tool to wipe other unnecessary files taking up space on your system drive.
4. 
5. After you do, you can click the More Options button and use the Clean up button under System Restore and Shadow Copies to delete system restore data. This button deletes all but the most recent restore point, so ensure your computer is working properly before using it.

Also, Windows will automatically remove the Windows.old folder a month after you upgrade, anyway. All those PCs that upgrade to Windows 10 will eventually have the space used by the Windows.old folder freed up.

I hope this helps in deleting the Windows.old folder from your machine.

Regards,
Lokesh