Deatroys all data registered to a session.

To kill a session we used session_destroy and session_unset().

But both are having diffrent meaning.
1. session_destroy is more effrctive than session_unset. session_destroy destroy session.

session_destroy() is use to kill the session.

2. session_unset only clear session but session also remain in just remove all session not remove session.

session_unset() in used to kill the session.