NOT an easy task....
With the amount of rebar in a Florida Pool it is very hard. Ever see the pics on the weather channel of pools on pilings on the oceanfront being stranded, by erosion, and STILL holding water? Removing one so a new one could be built was my task.
There is a bunch of re-bar coming to a "hub" in every radii. Steel every twelve inches in every direction is code. The radii are "built-up" with the spray gunite. Then there's getting it out of the hole.
My job, I was given because the owner and architect had more confidence in me, than well established demo and site work companies in our area. And it was a removal job, on a narrow lot surrounded by retaining walls. With a nearly complete House on the lot. Floor to ceiling glass faced the pool within five feet of the pool coping. (One of the reasons it was being removed, too close to the house which had been remodeled with more square footage) I used a BobCat 773 to shuttle the demo to two twenty yard roll offs.
I used a rented new Cat 312? Nine feet wide with a hammer on it that was four inches in diameter. It had no problem making holes, but was hard to connect the dots. Prolly was very good at punching holes, but sucked at severing the rebar. so I had a utility man with a consaw cutting every so often. In hindsight, I might have rented an acetylene torch set, but with both come the evil of rebar having some elasticity, if you understand my terminology.
Again, it was my intention to not leave anything larger than a golf ball before backfilling, and using equipment wisely was important.
For you? If you determine you can reasonably expect not to be impacted at a later date by the shell left in the ground, then you have gotten sage advice from above.
However, I will provide a caution not previously mentioned.
IF you had to sell the place, and a title survey turned up a pool once being there, and it isn't now, is it going to ruin the deal for the new owners? I'm unsure what legal ramifications there are, but I'd have to get an answer. (where I live, 60 year old houses go down every other day, to make room for new ones.)