unset session in php

1// Destroy a sesion variable name 'variable_name' 
2<?php
3unset($_SESSION['variable_name']);
4?>

1session_destroy(); // To delete whole session
2// OR
3unset($_SESSION['myVar']); // To delete a session var

1<?php 
2 session_start(); // start session
3 session_destroy();  // Delete whole session
4// OR
5unset($_SESSION['username']); // delete any specific session only
6?>

1session_unset();    //Destrol all session variables

1<?php
2session_destroy();
3?>
4
5

1
2All of a sudden neither session_destroy() nor $_SESSION=[] were sufficient to log out. I found the next to work:
3<?php
4setcookie(session_name(), session_id(), 1); // to expire the session
5$_SESSION = [];
6?>
7
8