BuddyPress.org

@postmarkj
It will always help to mention your using multisite when requesting support! In that case you need to go to Network Admin/Dashboard/Settings/Network Settings and to the right of registration settings check “Registration is disabled.”

@postmarkj
Have you went to dashboard/settings/general and unchecked “Anyone can register” to the right of Membership? Remember BP is a WP plugin and if you disable WP registration, you also disable BP registration.