The studs are just press fitted. I've most always been able to beat them out in reusable condition with a copper hand sledge hammer. Had a set stuck in real good once, piece of plate aluminum over the studs and one good whack with a 18 lb sledge was all it took. A press works great also.
When you go to reinstall the studs on a new rotor don't use your wheel to suck the studs back in, you will damage the wheel. Use a bunch of washers and the correct size nut instead. Impact wrench makes it much easier