BuddyPress.org

I don’t really understand when you want to disable the adminbar but this is a fairly easy thing. See: https://buddypress.org/forums/topic.php?id=1115 for the general idea.

You don’t want it on the root blog but you do want it on the subdomain blogs? You’ll have to wrap that in some blog detection code then. Disable it when global $current_blog->id is anything but 1.