locked file, how to release file in use

To find out which application is using a file in Windows and to release/delete/remove/overwrite file do following:
use processexplorer and search the handles (Menu/Find/Find Handle (Crtls+F))for the file you want.
This way you can easily find which process is having a handle to your file.
Then do right click + 'Close Handle' to release locked file.