Updates :: Not Enough Disk Space Freed

only 9 gigabytes of disk space appear to have been freed after deleting roughly 18 gigabytes worth of old Windows files via Windows Disk Cleanup. Since the Windows.old folder still exists even after the cleanup, I decided to check the folder properties to see if the folder still took up some space, but it was completely empty, save for a few empty subfolders that I didn't have permission to delete myself. I tried Disk Cleanup a second time, but it did not give me the option to delete old Windows files.