Restrict User to perform one function

Hi

Long time ago I saw a feature in 5.0.1 or 5.0.2 with user can be restricted to perform only one function

e.g when login with that use can only show Flow board

I know it is there but unable to configure.

need a hint to remember

The single app feature has been deprecated. To accomplish this now you would have to limit the ACL of the user and use a custom menu to reduce options

Is there any guide about ACL manage tips ?
Thanks
FER