67 Dart instrument panel

First, let me say I hope the dirty rotten *&(^%#$#$ that figured out how they'd put the instrument panel in died a long and horrible death!! With that out of the way....my question is how do you remove the wiring from the metal clip above the speedometer? I don't want to yank on 40 year old wiring with a lot of force.

Last night I was leaning toward 5 lbs of C4 but didn't want to disturb the neighbors.

I've already decided I will lengthen the left side panel plug/cable. I figure I won't be able to plug it back in very easily.

Thanks