Yah, I normally just grab a wire and yank hard, not!
I use a tool, grip the boot gently, always try to rotate the tool a bit to loosen the boot first, and apply a gentle in-line pull. I think these wires take heat and then simply bending them can cause a problem. The carbon core breaks down and cracks I'll quit whining, I got one tool that works but the angles are still tough, and the boots get baked-on. I suppose I could upgrade to a set of these to get the right angle to better grab them:
I can't justify the expense of those and the lifetime plug wire guarantee works. Now I have saved a full set of wires and have them ready when I need them. I wouldn't attempt a plug change without
a plug wire removal tool and a new set of wires available or at least a couple of long extras to get you by till you can get a full set. I think that's a good idea.
Maybe this helps someone else.
I was lucky to get replacements in this small town and should have checked before I started. I will be tuning again soon and I will pull a couple of the plugs, ones that are easier to get too, to double check my tune. We know there are reasons, perhaps upgrades which require messing with plugs before required maintenance intervals. I have lost plug wires three times now and have planned for it in the future.