If you're going to reuse the rotor, smack between lug holes on the wheel mounting surface. Otherwise smack the back side brake surface. Alternate across a diameter as mentioned.

If you get some movement but it won't come off, turn a lug hole to 45* between vertical and direction of forward travel. That should get the park brake star wheel in position for adjustment. Turn the star wheel as far as it will go in the 'loose' direction.

Sixto
87 300D