Buddypress is cool, has some downfalls, but is a great tool for building a wpmu driven community. Sometimes though, you get unwanted people wanting to create groups and cause a bit of havoc. I always set ‘Create a Group’ to be an admin task only. This is only a quick hack, so take it with a grain of salt.
In your /plugins/buddypress folder, you need to edit bp-groups.php, look out for the function below:
function groups_action_create_group() {
Once here, head down a few lines until you find:
if ( !is_user_logged_in() )
return false;
and change it to:
if ( !current_user_can('edit_plugins') )
return false;
Actually, this would be far better to include in your functions.php folder, I will save that post for another day.