Boot into Safe Mode and try deleting it. (To boot into Safe Mode, repeatedly press and release the F8 key while the computer is booting up. That will get you to the Boot Menu where you can choose Safe Mode).
Another method is to access the file through something other than Windows Explorer/My Computer (which are the same thing with different interfaces) by using a program that cannot open the file you're trying to delete.
For example, if it's a picture file, open Notepad, click on File>Open, navigate to the file you want to delete, right click on it and left click on delete. That bypasses Windows Explorer's insistence on indexing everything in the folder which can take forever or, if there's a corrupt file in the folder, will never complete. It's that indexing that most likely has the file "in use.'
A third method is to use
MoveOnBoot. It's a free utility that will delete the files you tell it to on the next boot before Windows loads and can interfere.