Get a construction specialist to inspect the wall prior to removing the pebble dashing. The pebble dash may be covering up an inferior wall construction. Ensure that it is safe to remove the stucco before proceeding.
Don the work gloves and eye protection. Remove as much of the pebble dashing as you can by hand. Start at the edge of the damaged area or at the edge of the wall. Hold the chisel at a 45-degree angle.
Hit the back of the chisel with the hammer until the stucco begins to chip off. Continue to chisel until you get all the way through the stucco to the wall beneath.
Remove the last remnants of the pebble dash with a high-pressure hose or wire brush.