Unlocker is an Explorer extension that allows you with a simple right-click of the mouse on a file or folder to get rid of error message such as error deleting file or folder, cannot delete folder: it is used by another person or program. Ever had such an annoying message given by Windows? Cannot delete file: Access is denied There has been a sharing violation. The source or destination file may be in use. The file is in use by another program or user. Make sure the disk is not full or write-protected and that the file is not currently in use. Unlocker is the solution.