How many ways you can delete a session variable?

In order to kill the session variable use:
  1. unset($_SESSION["test"]);
  2. session_destroy() — Destroys all data registered to a session
  3. session_unregister() — Unregister a global variable from the current session.
  4. session_unset() — Free all session variables.
To use the session variables again, session_start() has to be called.