Try a hand held power planer. Take it outside, set it to do a medum
shaving, and take it off a little at a time with each stroke. You wil
have plastic shavings everywhere.
You can't sand it, as it will load your paper in seconds. You can't
remove it with chemicals as the acrylics are just about impervious. I
don't know of any other mechanical means to remove it successfully.