Session unset, or session_destroy?

Unset will destroy a particular session variable whereas session_destroy() will destroy all the session data for that user.

It really depends on your application as to which one you should use. Just keep the above in mind.

unset($_SESSION['name']); // will delete just the name data

session_destroy(); // will delete ALL data associated with that user.

Something to be aware of, the $_SESSION variables are still set in the same page after calling session_destroy() where as this is not the case when using unset($_SESSION) or $_SESSION = array(). Also, unset($_SESSION) blows away the $_SESSION superglobal so only do this when you're destroying a session.

With all that said, it's best to do like the PHP docs has it in the first example for session_destroy().