Layer of keyboard circuit has blackout ink/paint?

I'm working on modding a keyboard that has built-in leds and bringing the circuit board closer to the surface so I'm not using keys. I'd like to do a custom layout or two that I can hot-swap, but the last layer of the circuit has a black layer on the opposite side of the circuitry (so removing wouldn't harm that layer) and I'm not sure how to remove it. I'm going to be experimenting a little, but if someone already has done it, please let me know.