On a networked computer, I have a file which is coming up as read-only because someone else has it open. This is not true. This is a file stored locally on the computer and it is not being used by anyone else.

I can login to the same computer using a different user, and the file opens up fine. I just get the issue with a particular user account.

Other than deleting theses account/profile and creating it again, how can I unlock this file?

Double clicking on this file gives me a message saying

The file is locked for editing by another user, or the file (or the folder in which it is located,) is marked as read-only, or you specified that you wanted to open this file read-only.

I don't think the folder is locked, because I can use other files in that folder fine, it's just 1 particular file which is causing this issue. I know that only 1 user is using this file as the file is on his c: and the same file works fine if he logs off to allow another user to log in.