The braking system of your car is extremely important to the safety of you, your passengers and other drivers. To understand how to maintain and repair this system yourself is a valuable skill. Removing the brake rotors is one of those key processes in understanding the operations of the brake system and how to repair it properly.
Remove the lug nuts that hold the rotor, or disc, in place. Set these lug nuts somewhere safe and secure so you don't lose them. If the rotor, or disc, is held into place by metal retainers, cut them off using diagonal cutters and discard them.2
Consider if you need to remove the brake caliper mounting bracket. This will depend on the make and year of your car. Consult your vehicle's repair manual for specific instructions on how to do this.3
Slide the disc off the nuts. If it appears to be stuck, do not force or hit it with a hammer. This situation needs to be resolved with care and patience. If the rotor's surface is struck, it can warp past the point of being reparable.4
Tap around the side of the "top-hat" surface. Tap around the studs, taking care not to hit any threads. Do this for a couple of rounds around the rotor or disc. It should slowly start to come loose and you can work it off of the lugs.