If you are referring to the valve itself, the answer is YES. You use a small tool that inserts into the valve core, unscrew the valve. Cup your hand over the core because as the valve gets to the end of the threads the air pressure in the tire will want to make it fly out.
If you are referring to the whole valve core and valve assemby, then NO.
You can just break the bead and remove only one side of the rubber from the rim and pull it thru one side. No need to take the tire completely off the rim, but a valve stem is inserted from the inside of the tire, and 'pulled' into place with a special tool (rubber stems), or screwed into place if a metal one.
To expand slightly on what in da zone said, the tool also has a tap built in to clean up the threads inside the valve stem. This plus a new core might be enough...unless your dog chewed the other one off or something!