You can unset session variable using:
session_unset– Frees all session variables (It is equal to using:$_SESSION = array();for older deprecated code)unset($_SESSION['Products']);– Unset only Products index in session variable. (Remember: You have to use like a function, not as you used)session_destroy— Destroys all data registered to a session
To know the difference between using session_unset and session_destroy, read this SO answer. That helps.