cast iron slop sink drain HELP!

I want to remove an old 1920's cast iron slop sink. The drain looks like it is puttied in. the trap says Lou Works and the number on it is P7298 it looks like cast iron. How do I get the drain to come out of this trap?
It has tons of build up on the inside looks like hard water scale. Thank you.

Without knowing exactly what you have I will give you one way to take them apart.

The drain should have a grid in it, if so you have to get a piece of pipe that just fits, cut two slots into the pipe that matches the grid, put it into the drain and use a pipe wrench to unscrew, if it's too gunked up to come out you will have to cut it out, luck.

The drain unscrews from the trap, and then the trap unscrews from the wall, but it may be easier to just saw the outlet pipe and slide the entire unit out of the way in one piece.