Although I have never cycled a tank this way,,,I would just leave it in there.Eventually it will breakdown to nothing,and as long as it is giving off ammonia,it will boost your bacteria to grow in numbers.I don't see how this could be harmfull to a tank that is cycling anyway...That is unless you notice that the ammo readings are getting REAL high.Say over 50...But if it has already spiked,I'd leave it be...