The [SiteAccessRules] rules in site.ini should allow to disable the /login and /logout from symfony.

Steps

1. Add to you site.ini.append.php file under override folder

[SiteAccessRules]
Rules[]=access;disable
Rules[]=module;user/login
Rules[]=module;user/logout

2. Clear the cache
3. Access to http://<host>/login

It displays the login form and allow the user to login when actually it should display the message "Module is disabled"