After upgrading to Windows 10, you may want to delete the old Windows directory (Windows.old), but when you try it tells you that you can’t. To delete the Windows.old directory you have to be a system administrator and delete the directory from the built in Disk Cleanup utility.
To delete Windows.old using the Disk Cleanup utility:
- Launch the utility from the start menu by typing Free Up Disk Space and selecting the utility
- Click Ok (assuming you installed to the C: drive
- Click Clean up system files
- Click OK
- Check Previous Windows installations
- Click OK
- Click Delete Files
- Click Yes
The Disk Cleanup utility will then delete the Windows.old directory for you.