PCB alterations post-production. Or, how do I not stab myself while scraping off the copper?
Assuming your PCB is low-voltage, then just a wide-ish cut from a scalpel will do.  Personally, I've had success with a technique akin to a lumberjack cutting a tree with an axe.  Put one cut in as deep as possible, then shave off bits from either side, making a "V"-shaped "canyon" until you're satisfied that the cut is big enough.  If your circuit is high-voltage, then make two cuts with a decent separation distance, then use the scalpel to cut underneath the trace and lift it off the board.

If possible, hold the board tightly in a vice whilst you're doing this, to allow you to have only one hand (the one holding the scalpel) near the blade.