How do I stop the rear brake pads from rubbing the rotor

You should have noticed if the caliper piston was hard to push back into the caliper on either side .. Jack up rear of car .. Pump brakes then let off pedal - try to rotate rear wheels .. IF either side is difficult to rotate, loosen blender screw to see if residual pressure pushes brake fluid out and wheel now rotates freely .. IF that is the case, suspect rubber flex brake hose has *collapsed internally* holding pressure on brake caliper piston .. IF opening bleeder screw doesn't help, suspect 'sticking' brake caliper piston... I have found that anytime brake caliper replacement is necessary, it's just good practice to replace the rubber flex hose as well (optional) ..... Also keep in mind the caliper has GOT to be free to move in and out as brake pads wear .. IF mounted 'caliper assembly' can not be moved, (pushed and pulled) then that needs to be corrected!!! .. Be aware that driving a vehicle with dragging brakes may result in unsafe operation and can be a potential fire hazard!