For the brake lever at the brake plate - remove the brake cable adjuster, unscrew the nut that keeps the lever on the brake cam, and remove the lever from the cam.
If you mean the brake pedal - disconnect the brake light switch wires, the brake cable, and unhook the safety spring (if there is a safety spring there) from the pedal. Then remove (unscrew) the bolt/grease fitting at the pedal pivot - that's what holds the pedal on the shaft. The pedal should slide off the shaft.