you've taken off the hub retaining screw? held on with a 5mm hex.

does the rotor feel as though when you pull it away from the hub it pulls back in as though by a spring? if that is the case then you have to loosen the emergency brake by it's adjusment screw in the hub.

If you know that you've released everything that holds on the rotor, a serious hard hit with a heavy hammer may be needed.