Prepare the Area
Turn off your main water supply, disconnect the plumbing pipes from the bathtub with a wrench, loosen the overflow slip nut, and then disconnect the tub drain with the wrench or channel-lock pliers.
Break the caulked seal around the edges of the bathtub with a flathead screwdriver and pull on the tub to see if it is loose. Go around the entire seal with the screwdriver as many times as necessary until the bathtub starts to move when you pull on it.
Take out a row or two of bathroom tiles in front of the bathtub to prevent them from being damaged.
Remove the Old Bathtub
Clear a path through your bathroom so the old bathtub can be taken out, and then insert a piece of scrap wood between the wall and the bathtub.
Stick the end of the crow bar underneath the bathtub and begin prying upward. As your bathtub lifts up, have your friend help you pull it out of its spot, being careful not to catch it on the plumbing pipes coming out of the floor and/or wall.
Carry the old bathtub out of the bathroom to a convenient location.
Install the New Bathtub
Carry the new bathtub into the bathroom and maneuver it into place where the old one used to be.
Connect the plumbing pipes to the connections on the bathtub with a wrench, connect the tub drain using channel-lock pliers or the wrench, and then turn the water supply back on.
Test all the functions of the bathtub. If everything works as it should, replace any bathroom tiles you had to remove and apply caulk around the entire edge where the bathtub meets the wall. This will seal it in place, so allow the caulk to set completely before using your new bathtub.