Any of the following can be used, each for a different purpose, or with a different mode of action:
Vinegar, Coca Cola, lemon juice, citric acid, other acidic materials (some are very strong). Removes mineral build up, which is often calcium carbonate.
Bleach. Breaks apart organic matter such as the bio film formed by microorganisms. Kills many microorganisms, but not all.
Rubbing Alcohol. Kills many microorganisms, but does not get into the bio film. If you suspect the tank or equipment has been exposed to Mycobacterium (any of several species or strains), use the bleach first followed by rubbing alcohol.
Salt. I sprinkle it onto a wet cloth, and rub the tank while the grains are still intact. Abrassive, safe for glass, removes stuck-on algae. Mild disinfectant: Many fresh water organisms cannot tolerate salt.
Drying. After any of the above, or after a thorough washing, allowing the tank and all the equipment to thoroughly dry can also kill some organisms.
Other disinfectants: Read and follow label directions, especially about what to use to neutralize and remove it.
NEVER combine ANY forms of cleaners, disinfectants or other such materials. Always thoroughly rinse the tank and equipment between various treatments.
Time (such as when you are doing the fishless cycle): Many diseases and parasites cannot live without a host. During the 3 weeks or so that the fishless cycle lasts certain organisms will be dying.
Side note:
I have used that dollar tree ammonia. It is very diluted. Add some, test... add some more... test... Make sure you give it some time to circulate. I ended up using the whole bottle to cycle a 20 gallon tank.