Who can change the Permissions of a group?

It is possible for the group owner or server admin to change the permissions level on a group after it has been created and populated with data, with the following limitations:

• It is not possible to 'reduce' permissions to 'Private'. Once links have been created in the database under 'Collaborative' (or Collaborative - Read-only) permissions, these cannot be severed. However, it is possible to 'promote' a Private group to be Collaborative or Read-only permissions.

See Permissions