Theme management

Hi,

I have Farms 133 installed for Pro Members of my multi-site, and provide a few themes like Kubrick, Twenty-ten, and WP Default for non-members.

But, non-pro members can also view my main "buddypress" theme (Edublog homepage) in their theme area.

How can I hide the Edublog homepage theme so it is not an option for non-Pro members?

Thanks.