How to delete files in computer used by another person or program

Some data files like videos ,songs ,wallpapers and some folders wont delete for long time.But some times they wont delete after restarting computer also.It always shows some popup windows like  "It is being used by another person or program". as shown in figure.

To delete this kind of files permanently or temporarily first download unlocker  .

After downloading unlocker install it...after installing unlocker it shows icon when you right click on the file or some thing .

1. Simply right click the folder or file and select Unlocker

2. If the folder or file is locked(undeleted), a window listing of lockers will appear

 

3. Simply click Unlock All and you are done! 

Thats it after clicking unlock all you can delete the file ..