I have a Windows.old folder left over from a previous installation of Windows, but every time I try to delete it, I get "Access is denied" errors or other problems. How can I get rid of this folder?
A Windows.old folder is created if you place a new installation of Windows on a drive that already has one, and you don't upgrade the old installation in place. The existing Windows folder is renamed "Windows.old," and any user-profile information is placed inside it in a /User subfolder. This makes it possible for users to place a fresh installation of Windows on a drive and then either automatically or manually migrate their user data.
Note that if you have a Windows.old directory -- or simply a remnant Windows directory -- on any drive other than the boot drive, this technique will not work. The Disk Cleanup utility only looks for old Windows installations on your current system drive. What's more, when you try to delete a Windows directory on another drive from within Windows itself, you run into permissions errors or other problems, just as you indicated.
To get around this, boot the installation media, go to the Recovery Console command line, and perform the delete operation there. This should circumvent any trouble you'd have deleting the folder conventionally.
This was first published in May 2013