Who do you hire to fill in an inground pool? Can anyone recomend someone in the Toms River area? 

I would contact a landscape company. And tell what your plan is.

I'm sure they can point you in the right direction.

You have to remove it first. 

I joking ask my neighbor who owns a pool company about filling in mine and his response was it’s cheaper to move.  Something about permits, DEP, and all the costs to rip it out and clean backfill it. To answer the question I would think anyone who installs pool could point you in the right direction if you want to remove it. 

The company I work for had a piece of property in Whippany with a hotel on it, it had a built in pool also, the company who leased the property wanted to remove the pool, they had to hire an engineering firm to draw up prints, the pool had to be cut and removed four feet down, the floor of the pool had to be jack hammered to allow water to drain, and all the fill had to be documented as clean fill.