What are you referring to when you say "There is ammonia in a clean H2O"?
If you mean the water you use has ammonia in it, you will need to change your source of freshwater immediately. You can purchase water from your local grocery store, although the parameters of the water should be checked (I'm assuming you can do this, as you've measured ammonia in your water source), and you may need to purchase buffers from your local fish store.
I use my tap water for my Bettababycakeswhoissobeautiful.
Good luck, respond asap so we can resolve the issue for your betta.