If you haven't laquered over it yet, peel away at it with your finger nail. If it breaks up, use a hairdryer NOT A HEAT GUN) to gently warm it and soften the glue. When the vinyl os gone, there may be some glue residue. If there is, put some white spirit or meths on it and give it afew sec to soak - the glue will turn to snot and will be removable with a clean rag. If there's any left then, just repeat.
BTW I know this as I'm a sign writer - I do this daily and it's the best way to remove WITHOUT surface damage.