Place your reciprocating saw blade into your reciprocating saw and secure it in place. Plug the tool into the nearest outlet or extension cord.
Position the reciprocating saw so that the blade runs parallel with the edge of the wall. Angle the saw so that only the front half of the teeth rests against the floor -- the back half should be elevated.
Squeeze the trigger to engage the reciprocating saw. Push the blade into the floor with firm pressure to prevent it from skipping around over the floor. The teeth should begin to tear into the floor.
Drag the saw backward once the front of the blade cuts through the entire surface of the flooring material. As you move backward, the blade will continue to chew away at the flooring material.
Pull up the flooring material once cut along the entire length of the wall. You should be left with a nice straight edge and be ready to install the new floor.