It is confusing and a mystery why there are two tc's in there, but there is a way to do it, you have to disable the second tc, and not the first, if you disable both you will get an entirely diffrent effect.
So in conclusion - disable the second towncenter, and only the second - IMPORTANT - If you want to disable other buildings as well, do it after disabling the towncenter, that way you will be sure that the right effect will occure.