MR,
Are you referring to the "chip guard" for rocker panels?
If you are, hold on to your shorts my friend.
This stuff is a urethane, and in my vast experience, there isn't a
product I've found to remove this stuff easily.
A DA with some 80 grit paper on it, is the only way I've ever found to
quickly remove this off rocker panels.
And seeing as your going to repaint the area anyway----Phooey!!

Happy Sanding,

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Terry 85 GL