<?php

if(isset($_GET['logout'])) {

    session_destroy();

    unset($_SESSION['uname']);

    header('location:login.php');

}

?>

<?php 

session_start();

session_destroy();

$_SESSION = array();

header("location: login.php");

?>

<?php

​

ob_start();

if (!isset($_SESSION))

    session_start();

unset($_SESSION['user_id']);

session_destroy();

header("location:index.php");

​