Your rotors are coated with teflon, and there is grease at the ends of the rotor pivot shafts. You need to protect this stuff. It'* not really necessary to clean them, but if you MUST, I'd remove the rotors and wipe them with a rag that has intake cleaner on it. Try not to disrupt the grease on the ends of the shafts, cuz I don't know what kind it is.
Same thing for the rotor housing. Rag with intake safe cleaner.