I agree with Rick_72. You are there, you are in charge, it's your class, your matts. If they are not mature enough to learn from you then that's tough for them. You were selected for a reason. Someone with that many years of experience is going to make sure their students are in good hands. Even if you don't feel authoritative BE authoritative. Project the air of detached professionalism - if they don't cooperate and you feel you need to have them removed from class then do so. Instruct them to meet with you and your sensei to discuss their issues openly and like a mature adult. Good luck, and congratulations.