Session Problem

hi guys,

I'm stuck with this problem, my session is still present even if i already remove it, session still showing when I click the back button, unlike INVO when you click logout and press back button it shows blank page with warning/error message

here is my code

services.php

<?php

use \Phalcon\Session\Adapter\Files as SessionAdapter;

$di->set('session', function () {
    $session = new SessionAdapter();
    $session->start();

    session_regenerate_id();
    return $session;
});

SessionController.php

<?php
class SessionController extends ControllerBase
{
    public function indexAction()
    {

    }

    /* get user from login/register form */
    public function registerAction(){

        $username = "testsession";

        $this->_session($username);
    }

    /* making session to be accessable */
    private function _session($usersession){

        $this->session->set('auth', $usersession);
    }

    /* end session */
    public function endAction(){

        $this->session->remove('auth');
        $this->forward('home/');
    }   

}

my Elements.php

<?php

use \Phalcon\Mvc\User\Component as Element,
        \Phalcon\Tag as Tag;
/**
 * Elements
 *
 * Helps to build UI elements for the application
 */
class Elements extends Element
{
    private $_tabs = array(
        'Home' => array(
            'controller' => 'home',
            'action' => 'index',
            'any' => false
        ),
        'Test1' => array(
            'controller' => 'test1',
            'action' => 'index',
            'any' => false
        ),
        'Test2' => array(
            'controller' => 'test2',
            'action' => 'index',
            'any' => false
        )
    );

    /**
     * Builds header menu with left and right items
     *
     * @return string
     */

    public function getTabs()
    {
        /* get session value in HomeController startSession method */
        $auth = $this->session->get('auth');

        echo $auth;

        if(!empty($auth)){

            $controllerName = $this->view->getControllerName();
            $actionName = $this->view->getActionName();
            echo'<ul class="nav navbar-nav navbar-right">';
                    foreach ($this->_tabs as $caption => $option){
                        if($option['controller'] == $controllerName && ($option['action'] == $actionName || $option['any'])){
                            echo'<li class="active">';
                        }
                        else{
                            echo'<li>';
                        }
                        echo Tag::linkTo($option['controller'].'/'.$option['action'], $caption), '</li>';

                    }

            echo'</ul>';

            echo Tag::linkTo('session/end', 'Log out');
        }
        else{

            $controllerName = $this->view->getControllerName();
            $actionName = $this->view->getActionName();

            echo'<ul class="nav navbar-nav navbar-right">';
                    foreach ($this->_tabs as $caption => $option){
                        if($option['controller'] == $controllerName && ($option['action'] == $actionName || $option['any'])){
                            echo'<li class="active">';
                        }
                        else{
                            echo'<li>';
                        }
                        echo Tag::linkTo($option['controller'].'/'.$option['action'], $caption), '</li>';
                    }
            echo'</ul>';
        }

    }
}