Windows 10 left a Windows.OLD folder to revert the machine back. That folder was chewing up 20+ GB of disk.
Microsoft claims you can remove it under the Windows cleanup, but no luck it would not delete the folder. Try deleting it as Admin, nope still cannot.
I came across a post that showed how to delete this stubborn beast via a command prompt. You have run the command prompt as admin. I keep a short-cut on my desktop to cmd.exe and to run it as Admin I right-click > run as admin.
- Take Ownership: takeown /F C:\Windows.old\* /R /A
- Modify Access Control: cacls C:\Windows.old\*.* /T /grant administrators:F
- Delete Folder: rmdir /S /Q C:\Windows.old\