code: protected function ivalidateToken($index, array &$tokenStorage)
      {
          unset($tokenStorage[$index]);
          $this->session->set(self::SESSION_KEY, $tokenStorage);
      }
docs: Invalidates the specific token by unsetting it from the tokenStorage
  array in the session.
  @param string $index Token index
  @param array $tokenStorage Token storage array with all tokens