Here are the steps to remove a cast iron tub:
1. Shut off the water supply to the tub and open the faucet to drain any remaining water.
2. Remove the plate covering the overflow assembly and take out the lever hook and drain stopper.
3. Place a piece of plywood over the top of the tub to protect it from damage.
4. Disconnect the walls of the tub and the overflow and floor drains.
5. Use a prybar, a sledgehammer, or an angle grinder to remove the tub from its alcove.
You can find more detailed instructions on how to remove a cast iron tub without destroying it at . If you want to install a surround unit after removing your cast iron tub, you can follow these steps at .
I hope this helps!