To delete some session data, you can use the unset() or the session_destroy() function.

The unset() function is used to free the specified session variable:
session_start();
if(isset($_SESSION['views']))
  unset($_SESSION['views']);
?>

You can also completely destroy the session by calling the session_destroy() function:
session_destroy();
?>

session_destroy() will reset your session and you will lose all your stored session data.