It is called the main jet, yes it needs removed so you can remove and clean the emulsion tube above it and clean all the little holes in it.
custom grind a good screwdriver to fit the screw slot tightly and properly.
Better to find one in a hex drive that comes in some in packages meant for a battery powered screwdriver/drill motors.
then you can put a lot on tension on it in a vice and a 1/4" drive ratchet without worry of it slipping out of the screw slot.