The challenge with any kind of masonry surface is cleaning the paint out of all those pores:

1. I’d begin by softening the paint chemically, using a biodegradable, water-washable deck stripper.
2. Follow up with a pressure washer that delivers more than 2000 pounds per square inch (psi) of force. A new wave of high-power pressure washers is coming out these days, and one of these may be necessary to get all the paint out of the pores of the brick. The best of these pack more than 3500 psi of water pressure – more like a sandblaster than just a cleaning tool.
3. Also, place plastic tarps around the area to catch the paint blobs. If the paint is more than 30-years-old, assume it contains lead and treat the residue as toxic waste.