I don't have it handy, but I'm pretty sure you have to rotate it either 90 or 180 degrees and then push the button and slide it off. Even so it was still pretty stiff. You'll think you're about to break it and then it pops off...:)
Peter M Thanks for the response. You are right. Snorkel side of the clip has to be rotated 90 degrees to either side. Then it is just a matter of pressing the release leaver and sliding the clip off. I appreciate the help.