Over 1 month passed, Method to back to Windows 7 from windows 10

Over a month — or if you’ve run the DIsk cleanup tool and removed the “Previous Windows installations” files or deleted the C:\Windows.old folder by hand — you’ll no longer see this option. Windows 10 appears to automatically remove the old Windows installation files after a month to free up space.

This works because Windows 10 stores your old Windows installation in the folder named “C:\Windows.old” on your computer. You can see this folder in File Explorer, though you shouldn’t attempt to delete it from here. You can also browse the Windows.old folder and restore files from it.

If you’re sure you don’t want to go back to your previous version of Windows, use Disk Cleanup tool to remove those files and immediately free up space.