Contao\FrontendUser::logout PHP Method

    public function logout()
    {
        // Default routine
        if (parent::logout() == false) {
            return false;
        }
        // Reset the auto login data
        if ($this->blnRecordExists) {
            $this->autologin = null;
            $this->createdOn = 0;
            $this->save();
        }
        // Remove the auto login cookie
        $this->setCookie('FE_AUTO_LOGIN', $this->autologin, time() - 86400, null, null, \Environment::get('ssl'), true);
        return true;
    }