First you need to determine if there is quality brass underneath worth saving. Try scratching the back side of a piece - if it looks good, then proceed.

Probably there's a layer of laquer covering the antiquing. A good paint remover will handle that (wear gloves, work in a well ventilated area or outdoors, etc).

Then you can determine if the object needs further sanding, polishing, buffing to get the finish you desire.

Bear in mind that once the protective coating is removed, the pulls will start to antique all on their own. Unless you plan on recoating them, you may wind up with pretty much the same look in a year or two.