The best way to delete the Windows.old folder is not to delete it in Windows Explorer, but to use Disk Cleanup.


  1. Open the Start menu
  2. Search Disk Cleanup
  3. If you have multiple drives select the one that you have Windows 10 installed on
  4. Click on “Clean up system files”
  5. If you get the User Account Control prompt click “OK”
  6. If asked again to select a disk, select the drive that Windows 10 is installed on
  7. Check the box next to Previous Windows Installation(s)
  8. Click OK
  9. You will now be asked to confirm the process to delete the files