The way to tell male guineas from female guineas is by the sounds they make. Males and females will make a rapid "ack ack ack" sound, and females with also make a two toned sound that sounds like "buckwheat, buckwheat". Only females make that sound. At eleven weeks they are probably all making their adult sounds now, but some may still be a little late to the party. If you're hearing any of them make the buckwheat sound it means they're female.
As for what to do with the male, you could eat him, rehome him, or keep him. Even if you don't want keets as long as you take their eggs from them they can't hatch them. Even if someone hides a nest from you and manages to hatch it, they are pretty bad mothers so unfortunately chances are good most if not all would die unless you took them to raise yourself.
