Your present bathtub probably is sandwiched between two walls, with the faucets and shower head located on one of these walls. You should be able to disconnect the piping and then pull the tub straight out. If this doesn't work, you may have to remove a wall section, cut the piping, and remove the tub through the wall.
Your bathtub may be freestanding, giving you open access to the pipes and fittings. Removal is simply a matter of disconnecting the piping and lifting the tub out. Remove the toilet and flush tank, or lavatory to make room (or lift the tub over these fixtures).
On this page, we show how the piping is disconnected/connected and the tub is removed/replaced when the tub is between two walls. If your tub is free standing, the steps will be similar. Here are the steps:
1. There may be an access panel on the backside of the plumbing wall of the bathtub. If not, this wall will most likely be finished with drywall, plaster and lath, or paneling. Remove the access panel of the wall surface so the piping is exposed. Find the wallboard joint and work from this point. Figure 1 should be helpful in locating the framing and piping.
2. Turn off the water before proceeding any further.
3. Disconnect the tub drain using a large adjustable wrench or Channel-lock pliers. Then loosen the slip nut connecting the overflow pipe that runs from the bathtub drain pipe. If necessary, remove the tub drain strainer, which will release the drain pipe below it (Figure 2).
If hot and cold water faucets are inside the bathtub (not above it), remove these fixtures back to supply connections.
4. Remove the wall covering (such as tile) from around the tub. One course of tile is plenty. Use a hammer and cold chisel for this and wear safety glasses to protect your eyes from flying debris (Figure 3).
If the wall is not tiled, remove about four inches of material to expose the clips holding the tub. These fasteners will be attached to a ledger strip around the tub. Remove or disengage the fasteners. The tub may simply sit directly on the ledger strip (Figure 4).
5. With a prybar and a piece of scrap wood to protect the wall (if needed), gently pry the tub away from the wall. Go completely around the tub. With a helper, try moving the tub out a tad more. If you meet any resistance, chances are the tub is not completely disconnected from the water supply and/or drainage system. Go back and check this.
If you find a hang-up, disconnect it or reposition it. Then try moving the tub again.
6. Hopefully, you will be able to move the tub straight out from the wall. If so, put down some 1x4 skids or a piece of plywood so the tub won't damage the floor as it is moved out and so the tub is easier to slide. You will need a helper for this; bathtubs weigh plenty. Don't try to move the tub alone.
If the tub can't be removed by sliding it straight out, remove the wall opposite the faucet and exit here (Figure 5). This will involve cutting framing members, which you will replace later. However, the wall may be load bearing and you must shore up the framing -- before you make cuts -- with two or three lengths of 2x4 or 2x6. If you are unsure about the house structure, consult a building contractor, engineer, or architect.
If you can't get the tub out of the back wall, it will have to go through the plumbing wall. The pipes will have to be cut accordingly and capped. If the pipes are plastic or copper, you can remove them with a hacksaw just above the opening for the tub.
If the pipes are galvanized steel, you may be able to disconnect them at the coupling. Use pipe wrenches for this. One wrench goes on the fitting and the other one on the pipe.
Put down skids for the tub, as suggested above, and have a helper assist you in the tub removal. When the tub is out, you can lift and carry it with aid of helpers.