Remove the wheels, then remove the brake calipers to get them out of the way to access the rotors. The brake calipers are MOST ALWAYS bolted with ( 2 ) large caliper bolts with a large allen head on them, two bolts for each caliper. Once the bolts are out you can slide up or call it "prying up" so to speak the caliper unit off of the brake rotor. Now you have clear access to the brake rotor there can be either ( 1 ) star or allen head screw on the face of the rotor that keeps it on the system or you may have a center cup that is pressed on that hides a large nut behind it. If so grab a screwdriver and a hammer and tap the crease of the cup to pop it off, make sure you don't destroy it or something being impatient. Once the cap is off you need a large socket like maybe 28mm to get the rotor nut off and it will come right off. All set.
