Yes, you can disable the user registration in Dashboard > Forums > Settings > Features Tab.

Then disable the user registration in WordPress settings: Dashboard > Settings > General Tab

Then remove login / register menu in Dashboard > Appearance > Menus admin page. Choose the to access wpForo menu.

Then enable guest posting for each forum, here is the instruction: https://gvectors.com/how-to-enable-guest-posting-on-wpforo-wordpress-forum-plugin/

Dashboard > Forums > Settings > Features Tab

Set "Enable User Registration" to no

and allow guest posting (Forum Accesses) and (Usergroups and Permissions)

is there any way to deactivate logging-in and registration so that any one is free to make comments on my forum boards without having to register?  i want an open forum.. no membership.. is it possible?

thanks

Lord-have-mercy