Destroy session in logout

I wrote

public function logout()
    $result = $this->Authentication->getResult();
    // regardless of POST or GET, redirect if user is logged in
    if ($result->isValid()) {
		$session = $this->request->getSession();
        return $this->redirect(['controller' => 'Users', 'action' => 'login']);

I had to guess as where the session destroy belonged. I don’t know if I put it in the right place. Maybe it should come before the if condition? It’s working but I’m not sure it’s correct.