I cannot find, how to have moderators or key masters be able to ban users – without them also being ADMIN on the WordPress site ?

Have I missed something ?

(lastest version of everything -wordpress+bbpress etc.)

[@anonymized-5853594 Inactive 11 years, 4 months ago]

As far as I can find, you can only ban them with an Administrator. The users are an inherent part of the WP install and bbPress only makes use of the function. So editing things from users beyond forum moderation is up to the Admin.