Should have known there was more to it

I'm trying to replace a plastic shower pan I belive was placed/inserted over tile from the pervious homeowner (Not sure) I have removed the shower door and removed the caulk surrounding the pan, I have also removed the drain cap but not the overpiece that is over the drain entrance overlapping the plastic shower pan., I guess my question would be at this point 1) how do I remove the old shower pan 2) should I hire someone one for this 3) HELP

The reason I am replacing the plastic insert pan is because it has a hairline crack starting from the drain heading outward