These are the ways on cleaning your rotors while they are on your vehicle:
Step 1: Unscrew the screw and remove the wheels
Step 2: Thoroughly spray brake cleaner on the brake area, use soap and water
Step 3: Make sure to spray the calipers and rotors
Step 4: Use a microfiber cloth or regular rag to wipe the rotors and the outside of the calipers
Step 5: Put the wheels back on and lower the car to the ground
Step 6: Start driving, the brakes will continue to clean by itself