Removing a pool is absolutely a non trivial process. It does require a permit and it is not cheap. Deckover is an interesting alternative as it does give you an out albeit a fixed one. I am by no means any expert about deckover or removing a pool at all but many people make assumptions that removing a pool is trivial and some people have even thought they could simply fill a pool in on thier own, which is not true… at least not without violating code.