unset session in php not working code example

Example 1: unset session in php

session_unset();    //Destrol all session variables

Example 2: session value not removed php

All of a sudden neither session_destroy() nor $_SESSION=[] were sufficient to log out. I found the next to work:
<?php
setcookie(session_name(), session_id(), 1); // to expire the session
$_SESSION = [];
?>