Suggestions on demo'ing a concrete lined pond/pit

I want to take out what was, a long, long time ago, a fish pond. Now it’s a mosquito factory and we’d hoped to drain the standing water and puncture the membrane to allow for drainage. Haha!! Instead we found out that it’s thick concrete on all five sides and will be a much bigger problem to solve. Also, it’s located about midway on a narrow bed/island that’s raised about 6-8″ off the ground and delineates by yard from my neighbors. I want to bring it all down down to ground level as part of this pit project.

So, I’m looking for both suggestions on how to best handle as well as recommendations on who to work with. My handyman thinks we should just fill the pit with the material from the island and level everything out, which makes sense to me, but I want to make sure there’s no need to break up the concrete in the pit…at least the bottom, so that the soil and rock placed in will properly settle to avoid any sinkhole at a later date and to properly drain in case plantings are put here later. That’ll require a jackhammer, in a tight confined space.

And then, who are the right guys for this type of job? Perhaps a demo crew? Or hardscapers from a landscaping design company? Any recommendations?

I want to rectify this asap so that all is level again and I’m not breeding mosquitoes in my yard!

Thank you!