Remove any screws or nails that attach the threshold to the floor with a screwdriver or hammer with a nail puller.
Cut any screws or nails between the threshold and the door jambs. Situate the reciprocating saw so that the blade will cut between the threshold and the jambs of the door. In most pre-hung doors, screws or nails attach the threshold to the door jambs.
Pry the threshold so that it will slide out from under the door. Loosen the jamb with a flat-head prying tool, or by tapping the threshold with a hammer.
If you can't pry the threshold loose, the door framing may be covering nails or screws at the edges of the threshold. Use the reciprocating saw to cut any nails or screws under the threshold. Pry up the threshold with a hammer claw or prying tool so that the blade of the reciprocating saw will fit under the threshold. Finally, remove anything that may be attaching the threshold to the floor.