You could move the court to have your record sealed, but since it is a juvenile record and assuming you haven't picked up anything again, then it would not be visible to the public anyway. As far as your chances of being a police officer, you will have to report the arrest because it is law enforcement. But unless it was a violent crime and you were adjudicated delinquent, it is unlikely to affect you. Above all, don't try to hide it. Be upfront about it when applying to be a police officer and it sounds like you may be able to explain this away. Good luck.
It is highly unlikely the arrest would affect you in anyway. As for sealing or expungement, while I think it is a good thing for you to pursue overall - it would not be hidden from the view of any law enforcement agency.
Please visit my website at www.richardhornsby.com/criminal/record/ for more information on sealing and expungement.
My colleagues are correct. Be honest up front about your history.
Expungement is only available for cases that are dismissed. Sealing your case would not prevent law enforcement offices from viewing your record. The Florida Department of Law Enforcement has a list of entities that get sealed/expunged records and the first item is candidates for employment with a criminal justice agency.