The short answer is that if it is actually sodium hypochlorite added, it can easily be neutralized with a sodium thiosulfate solution readily available in aquarium shops, sold as one brand or another of "dechlorinator". This is usually the cheapest aquarium water treatment option on the shelf, and for me it has always done the job well. If it's chloramine added to the city water (which is more common now), the usual recommendation is to double the dose of dechlorinator. It should be safe to err on the high side. It could lower the pH if you really seriously overdo it, and it adds a little sulfur. Some ammonia is released when chloramine is neutralized with sodium thiosulfate. I have never had a problem that I could trace to this. It would be most likely to be a problem in an initial setup or large water change in a high pH tank with no biological or chemical filtration that targets ammonia. Some dechlorinator type products claim to also detoxify this ammonia.