Removing cerakote from metal is not too big of a deal. Aircraft remover and some elbow grease. But, if you are planning a differnt color, it's really much easier to degrease, scuff and refinish.
Removing a powder coat finish from fiberglass (carbon fiber uses the same epoxy base) is a real delicate operation. As stated, you can blast it but you had better be skilled and be paying attention. Aircraft remover is highly likely to attack the epoxies used in the fiberglass so definitely not the way to go. Again, if you are planning to refinish with anything...krylon, cerakote duracoat, etc...just degrease thoroughly, scuff some to promote adhesion of the new finish and apply your new finish.