Only by water washing.
Bricks don't rust
A good way is to pressure wash the bricks. This will remove the moss and clean the bricks at the same time. It's good that you pressure wash your fences and outdoor walls regularly.
Remove it :D
can you explain how the kidneys remove wastes and keep fluids and salts in balance?
with a hammer and chisel
to remove salts in the blood
I suspect they are after the salty taste as a result of the salts in the cured mortar.
Possibly scrape it off with a scraper if it is thick enough to do so.
Salts remain as a solid residue, water (or other liquid) is evaporated.
for a neat opening you must cut the bricks with a wet saw then remove the inner bricks. For a rough opening drill or crush a brick in the center and remove the bricks around that. Be careful, if you are making a large opening there is a chance the bricks above the new opening will fall as they are no longer supported.
can you explain how the kidneys remove wastes and keep fluids and salts in balance?
To efficiently remove mortar from a brick wall without causing damage to the bricks, you can use a chisel and hammer to carefully chip away at the mortar. Be sure to work slowly and methodically to avoid damaging the bricks. Additionally, using a mortar removal tool or a grinder with a diamond blade can also help remove the mortar effectively while minimizing damage to the bricks.