logout.php

<?php
// Initialize the session.
// If you are using session_name("something"), don't forget it now!
session_start();

// Remove session json file
$session_file = session_save_path()."/json/sess_".session_id();
unlink($session_file);

unset($_SESSION["username"]);
unset($_SESSION["firstname"]);
unset($_SESSION["lastname"]);

// Unset all of the session variables.
$_SESSION = array();

// If it's desired to kill the session, also delete the session cookie.
// Note: This will destroy the session, and not just the session data!
if (ini_get("session.use_cookies")) {
    $params = session_get_cookie_params();
    setcookie(session_name(), '', time() - 42000,
        $params["path"], $params["domain"],
        $params["secure"], $params["httponly"]
    );
}

// Finally, destroy the session.
session_destroy();
//die("Logged out");
header("Location:csrf.php");
exit();