From memory, I think you want to get your ammonia to 5ppm, until you get nitrites (don't quote me, but I think this is right)Use 100% pure ammonia.
Using a dropper, add 5 drops of ammonia per 10 gallons of aquarium water. If you don't get an ammonia reading with your test kit, add some more drops until you start to see an ammonia reading. Keep track of how many drops you've used so you can repeat this process daily. Continue to dose the tank with ammonia until you start to get nitrite readings with your test kit. Once you can detect nitrites you should only add 3 drops of ammonia per 10 gallons of aquarium water, or if you added more drops originally to get an ammonia reading cut the amount of drops used in half. Continue this process daily until you get nitrate readings with your test kit. Do a 30% water change and your tank is ready.
Actually I am pretty sure if you have enough you can kill it, but you need like 8 even 10+ppm in order to do this! If you have that much I would just dump the thing and start over!!! ;Dryanr said:note: I don't believe that you can kill your bacteria persay, it might just mean that it takes longer for the colony to grow large enough to remove all the ammonia ???