It doesn't actually remove it, it converts it to ammonium, which is harmless to fish, but available the same as ammonia to your bio filtration. Products like Ammo-Lock are made with sodium hydroxymethane sufinate, or a similar compound.
The Nesler reagent test, which is a single reagent test, will give a false positive when using Ammo-Lock or a similar product, as it reads ammonium the same as ammonia. The salycilate ammonia test, which uses two reagents, will not read ammonium as ammonia.
None the less, you are solving the symptoms and not the problem using a product that converts ammonia to ammonium. It is something to consider keeping on hand, as long as you know it is more of a band-aid product than a solution to the problem.