DON'T BEAT ON ROTORS WITH A BFH UNLEES YOU WANT TO REPLACE THE WHEEL BEARING IN A FEW WEEKS
Not smart!
If you need to get it off and some persuasion with a reg ular hammer doesn't work. Don't go pulling out the sledge. You will need to cut the old rotor off with a diegrinder.
Cut down through one whole side of the friction srface and part way through the hat, avoiding cutting trhrough the hub itself. Then insert a chisel into the cut and hammer it in - the rotor will crack easily and you will be able to remove it.
Beating on it will a mallet will Brinnel the wheel bearing sand then a simple brake jobs ends up in a wheel bearing replacement.