Changing To Just Lines?

Okay, so currently I’m working on a small animation in Toon Boom Studio (about two seconds and 24 or so frames), but I needed to change the design of the character in it.

I need to find a way to completely erase all the color from inside the lines, but the Unpaint tool is a bit confusing, because this is the second time I’ll be changing the character design.

Thanks to anyone who might be able to help!

In your Colour Palette select Style / Duplicate Style…
Then select Style / Tint Offset / move the Alpha slider to 0 (zero)…

Thanks for the help, I did that and almost all the color disappeared, now it should be easier to erase the colors and start over.