To remove the rotor's ( I just did a week ago when replacing brake pads and new rotor's) you first must take off two assembly's. The caliper has two bolt's on the inside and the other assembly which holds the brake pads,also has two bolts on the inside which hold this on. They can be difficult to separate as the caliper piston has pressure on it against the pads and the rotor typically has a rim of rust around the outer circumference but can be pried apart. With that many miles I would replace the rotors and as long as it is apart, I would't re-use the old brake pads as old pads and new rotor's don't make sense as long as it's apart and I believe not recommended. To be able to turn the rotor's, there must be enough material left to do so and there's a minimum dimension required. Good luck!