Yes you can... One option is before you drain it put in the amount of dechlor for that size tank, and mix it in before you drain. Otherwise just let it sit... The chlorine will dissipate over a day or two, but dechlor (any brand) will get rid of it immediately. If the tank/python smells at all like chlorine then fill it and dechlor it again. Depending on the brand it should be around 7-13 teaspoons for a 65 gallon tank. It's not really too big an issue since any chlorine will have dissipated long before the tank is cycled, and ready to stock at any rate. Just make sure there is no smell in the python before using it on any other tanks.