Kills PHP session.

session_kill.php

<?php

// NOTE: see http://www.php.net/manual/en/function.session-destroy.php
function session_kill() {
  // Unset all of the session variables.
  session_unset();
  // $_SESSION = [];

  // 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();
}