only admin can create group for ver 1.8

I was able to limit only admin can create the groups by following this disccussion

http://community.elgg.org/pg/forum/topic/613304/only-the-admin-to-create-group/

However,there are alot of changes in v1.8. It seem new approaches has applied in the new version of elgg.

So, my question,

I want only the admin to create groups, how do I acheive this?

Anybody know how?