Is it intended to use the achievements system (with badges), but to not use ranks? I don’t see an option to deactivate ranks. I tried to simply delete all ranks but it still shows in this awkward way:

There isn't really a facility for switching one part off at the moment, but it should probably be suppressed on the front end when there are none to show. I have added a bug report for that

This issue has been resolved in 4.7.0 which has recently been released. Please upgrade to that version to resolve this, and of course, let us know if you are still seeing any issues.