5 Ways To Delete A File In Use In Windows [View all]
http://www.makeuseof.com/tag/5-ways-delete-file-use-windows/

Windows Explorer thinks the file youre trying to delete is still open, but its not? This commonly happens with video files that were played back in Windows Media Player but it can happen with any other file, too. The file is either running in the background or it wasnt closed properly. You can even run into this issue with files you havent opened in years! Fortunately, this can be resolved in a few different ways.

Did You Close The Program?
Lets start with the obvious. Did you just open the file and not close it? If the file is closed, but the program is still running, close it too, then try again.
Have You Tried Rebooting?
Rebooting solves most issues and it will most certainly solve this one. While it can be inconvenient, it requires zero skills or fiddling with stuff like the Task Manager or third party tools. Rebooting also clears your RAM and possibly fixes other nuisances in one go. So try this if you cant be bothered to look into the cause.
If you have already tried rebooting and it didnt help, skip the following steps and go straight to third party tools.
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