Never done it, but I've seen these in pieces & with different coloured knobs on them, so they definitely come apart. Im sure the little cap on the end of the multifunction switch pops out, (I would use a pik tool, or point of a test light). When the end cap is off, you can see little fingers or claws holding the twist bit on to a shaft, if you push the claws apart, the knob will come off.

Good luck
Max