Unfortunately, the picture did not show on my computer, so I'm handicapped here ... However, you will not get a clean edge where you want to without sawing the brick. If the wall is damaged, just repair it (drywall? plaster? who cares?).
A few weeks ago, I took out a wall which was filled with both concrete and rebar. Get ready for a workout. The chisel bit in a rotary hammer is great for bulk work but it can break bricks you want to save.
When you get close to the final edge, go to the saw. Masonry blades are smelly but cheap. Diamond blades are best but expensive. Rent a saw and burn through the masonry blades. You might also have to use an angle grinder (with a 4 1/2" diamond blade) for precision work.
Remember to really protect your floor ... tape cardboard to it for best results and remember bits and pieces fly a long way ...
I'd like to see another pic if you can repost ... might have more thoughts.