The usual way I use them is,
unscrew the plastic cap, then the large nut just below it(holds the valve core in place). this lets all the air out.
next unscrew any nut at the base of the valve; so you can push it out of the rim.
dismount tire, pull the inner tube out.
toss it in the trash.
reinstall and reinflate tire with a shraeder valve tube.