Woah, be careful here. 'Painted' carbon fibre may not be painted at all, but actually have a coloured gelcoat (the outermost layer of structural epoxy). I've no experience of carbon bicycles, but I've worked with carbon fibre before and coloured gelcoats are common. There's no safe way to remove a gelcoat, so the only way of changing the colour would be to paint over it.
Woah, be careful here. 'Painted' carbon fibre may not be painted at all, but actually have a coloured gelcoat (the outermost layer of structural epoxy). I've no experience of carbon bicycles, but I've worked with carbon fibre before and coloured gelcoats are common. There's no safe way to remove a gelcoat, so the only way of changing the colour would be to paint over it.