To remove a cast iron bathtub from a bathroom, disconnect water supply to the tub, drain the tub, disconnect it from plumbing, remove the framing surrounding the tub, and piece the tub with a sledge hammer. Collecting and discarding the broken pieces completes the process. Be sure to protect yourself from being injured by tub particles by covering the tub with a tarp during the breaking process.
To disconnect the water supply to the tub, locate the tub's inlet valve and turn it off. Empty the tub by turning on its drain valve and allowing all water to escape. Using a sponge, blot the tub dry before detaching the tub from the plumbing that serves it. Then, protect the drain hole from blockage by plugging it with a rag. Remove the bathtub frame by prying out the caulking and tiles bordering the tub's edge.
To piece the tub, start by breaking off its cast iron on the outer part. To do this, hit the tub's middle, outer part, taking care to grasp the hammer properly. Hit the cast iron repeatedly into portable pieces. Remove the pieces, and repeat the process to break the inside of the tub before carrying away the pieces. To ease your work, remove the broken pieces repeatedly once they form as you continue with the breaking process.