One way to "remove" ammonia from the tank without changing water is to decrease the pH of the tank. Doing this will convert the ammonia molecules into ammonium ions and if the pH of the tank were to become more alkaline then more and more ammonia would reappear with increasing alkalinity.
I didn't see what fish are in the tank, but it was mentioned above that you may have cichlids (Africans I'm assuming) so decreasing the pH isn't a good idea in my opinion.
Another option may be to add live plants, however mixing plants and Africans generally ends up in destroyed plants, though you may find success with some species/arrangements.
A more "realistic option" would be to use zeolite to remove ammonia from the tank, but your tank is far overstocked and you would need a great deal of it to work.
I recommend water changes of 15-20 gallons 2-3 times per week. You could always add zeolite to your filter in order to prevent ammonia spikes. Might even consider some floating plants like duckweek or Amazon frogbit, though I'm not certain that they won't be eaten.