[Lynne]

Define 'closed'. If the forums are closed, no one can see them. So, you want a sign on your social group page that just says the group is closed (and nobody can see a thing)? Or do you mean you want to be able to close it to users joining? Or close it to posting?

Anyway, whichever of those you mean, you will have to modify the code. Depending on which it is, it could just be a simple plugin that you need to write.