... to what Jim has said. If you 'paid' for the pool when you bought the house, by filling it in or destroying it will 'cost you' down the road. When my wife and I were looking at homes years ago, where there was a pool, we use to tell the Realtor/Seller that we don't want the pool so 'cut the price'. None were willing but we never followed up on them to see if they 'cut the price of the house' to compensate for not selling when WE were looking. This is what I mean when I said 'paid for it.'
I would say that if you're gonna spend ANY $$$ on this, I'd look into 'capping' the pool as Jim suggests. If it costs $1,500 to 'dig out' the bottom, and backfill with dirt, spend the $$$ on capping it! At least later on, you may have a good bargaining chip.
FWIW, I kid you not when I tell you this. An older woman behind our home lost her husband a few years ago. Last summer, she finally did something w/the inground pool. She has some company 'knock' the concrete walls inward, fill it with dirt, and plant some grass. Well, this year, she has a 'sink hole' in her yard! Poured concrete chunks and walls don't 'mix' well with dirt. Apprarently, there were a LOT of 'cracks and crevices' under there that 'sucked' in the dirt that was brought in. And here it is almost July and I haven't see the contractor come back to 'finish' the job. Maybe he's telling her to wait a few more years to be sure the settling has stopped. Sure! By then, he's Out-Of-Business as 1 company, and in business as another!
Well, anyway, 'nough said. My best to ya and hope this helps.