I assume you are referring to the clip which slides over the two metal vacuum tubes on the bottom of the air cleaner base. If so, they are stubborn to remove. I found the using two long sockets, 1/4" and or 3/8" over the tube and pressing down with enough pressure to flex the clip towards the air cleaner base the valve will drop out or can be wiggled out of the clip. There are two tiny tabs holding the clip to the tube and the more you try and pry the clip off the more it grips the tube, so the idea is to get the tabs to flex outward to loosen their grip on the tube. You can also use one socket and work each side a little at a time.
