Are they under the clear coat or over? Makes a big difference. If over, yeah, something like Goof Off or acetone is harmless to the carbon/clear coat if they just won't peel off.
If under the clear coat, start sanding, and stop if you hit black powder. I sanded some decals under the clear coat off some asian 50mm deep-v carbon clinchers. Took about 4hrs for all 12 decals. 3 per side each wheel. Then, I hit it with clear coat from the local big box home store in flat clear, wet sand to smooth it....sweet looking now.