Hi Ron,
If your ultimate goal is to tile over your brick fireplace, there's a couple of things to keep in mind. Off the top - don't remove the existing brick, as it's there to protect the fire box and under no circumstances should you compromise its structural integrity. Secondly, you need to keep all combustible materials eight inches away from the sides and 12 inches from the top of the fireplace opening. You can give yourself a flat surface for installation by covering the brick with Durock cement board first, and then installing your tile.
Hammer on,
Jim