How can I delete the file if access is denied?

Q. How can I delete the file if access is denied?
A. Impossible deleting the file if:
1. Access is denied.
2. The file is in use by another program or user.
3. The source or destination file may be in use.
4. ....
The best option is download free Unlocker: http://ccollomb.free.fr/unlocker/#download (Unlocker 1.8.7 - From this website )
Install that program. Next, right-click on any file and choose Unlocker and option delete. Done.