Cannot able to Delete Files or Folders ?

When ever we try to delete some files or folder in our PC some times it shows an error like this

* 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.

or some different errors like