Honestly, this right here kinda reads like you are too lazy to go do what needs to be done yourself.  Most of us learned by just doing.  Pretty sure I ruined a clip when removing the first one maybe 20 years ago, but I figured it out pretty quick after that.  I've pulled mine apart in the past, but I honestly haven't been inside the dash in so many years that I'm going off memory.  It should come apart as I said, but I believe there's the same type of clip on the heater control valve in the engine bay that you could more easily see.  The flat bottom portion should have a notch or detent, or the top piece might be such tight spring steel that it is held in place without a notch.  But either way, the flat bottom and top portions just unclip from each other and the cable slides out sideways.

Has nothing to do with being lazy, it's just not THAT important to me, I will not take my whole dash apart just to replace this cable. I have plenty of other projects to do on this truck. But I can see the cable and clip through the ash tray, it's tight but if it was possible to get the clip off from there I would do it.

I know you said it's been 20 years since you've messed with the heater control panel but the clip is nothing like the one on the heater valve, this one is plastic, not metal and shaped completely different.