src/web/Session.php
public function remove($key)
    {
        $this->open();
        if (isset($_SESSION[$key])) {
            $value = $_SESSION[$key];
            unset($_SESSION[$key]);

            return $value;
        } else {
            return null;
        }
    }
public function remove($key)
    {
        $this->open();
        if (isset($_SESSION[$key])) {
            $value = $_SESSION[$key];
            unset($_SESSION[$key]);

            return $value;
        } else {
            return null;
        }
    }
Removes a session variable.
@param string $key the name of the session variable to be removed
@return mixed the removed value, null if no such session variable.