If, when removing the Cardellini clamp, you find the sliding jaw bound on the shaft, loosen the knob just a couple of turns, then wrap your fingers around the shaft and use your thumbs to pull the back end of the jaw toward the knob.
If this doesn’t work, a light tap on the back end of the sliding jaw will free it. Should the sliding jaw stick on the shaft after the clamp has been closed and stored, simply rotate the jaw to free it.