How to Install a Bathtub: Removing the Old Tub
The worst case scenario is that you will have to break a small hole in the wall to turn off the water. If you do have to do it that way, try to do it from the back side in a closet and then go to the extra trouble of installing an access panel. You will be saving yourself more work down the road if you ever have a leak inside the wall.
2. Remove Handles and Spout. After you have the water turned off, remove the handles and fill spout. The spout should just twist off. You can probably do it by hand, but if it's tight, use the wrench. If you're going to re-use the spout, pad the jaws of the wrench with a rag. If not, then twist away.
Once the spout is off, you can move to the handles. Most are held on with a set screw. These can be removed with an allen wrench. With the handles and spout gone, you are now ready to remove the tub.
3. Take Out the Tub. One of the biggest challenges to installing your own tub is maneuvering your old tub out and your new tub in. Bathrooms aren't typically the biggest rooms in the house, and the logistics of getting a large heavy object in and out of the door can be a little complicated. If you have an old cast iron tub, or if you purchased a new cast iron tub, you probably aren't strong enough to lift it up over your head to get it out of, or into, the back corner of the bathroom.
Most of the time, removing the toilet before you start will give you a lot more room to work and will keep you from having to lift a very heavy tub up and over. Sometimes it is necessary to remove the vanity as well. This will be true if your vanity or toilet is right up against the tub. There simply won't be enough room to pull it out from the walls that it is sandwiched in between.
Once you have the toilet removed, or are confident that you have room to work, use the pry bar to break the old tub free from the floor. If you are going to save this floor, then take care not to damage it when you are using the pry bar. Put a towel underneath any fulcrum point and make sure that, if the floor is ceramic, you use a thin piece of wood as a buffer between the floor and the bar to insure that the tile does not crack. After the tub is free, you should be able to pull it straight out.