If it's an M-B rotor, they state that the rotor can be installed as is and the coating will wear away quickly with use. It won't ruin the pads. And you have to take it easy the first number of stops.
If you still decide to remove the coating, don't just use mineral spirits as it leaves a film on the metal. Final washing should be done with alcohol, brake cleaner, or lacquer thinner.
95 E320 Cabriolet, 131K