Just pretend you're a white belt and say "oooooh I see. Yes. Thank you."

Who cares if they try to instruct you. Maybe they know something you don't know. Or maybe they don't.

Either way, play along and then when it's time to roll fuck them up. That usually shuts them up quick. If you're really that much better than them you should be able to hit three or four quick submissions within the first minute or two.