I need a little more information, but in general, you cannot erase a DUI unless you got a withhold of adjudication or completed a diversion program. I would advise you to see an attorney and he/she can help you get the process started.
I am going to assume that you were actually convicted of this offense and not just arrested and then had the charges dropped. If you were in fact convicted of this, then you cannot get it expunged for two reasons. First, expunge means to have it erased because the charges were dismissed or something similar. Second, Florida law requires a mandatory adjudication on DUIs, which means you are not eligible to have it sealed. The only exception to this is if you received a youthful offender sentence with a withhold of adjudication.
Of course, the facts of your case are unknown to me, so my answer is based on generalities. You should contact an attorney that practices in that area to assist you further.
Once cannot expunge a DUI in the State of Florida as a DUI in almost every circumstance requires that you be adjudicated guilty. The onlye xception I am aware of is if one is sentenced a youthful offender. This would mean the DUI was a felony and you were under the age of 21 at the time of the offense.
You need to get a copy of the judgment and sentence in your DUI case to determine how the judge adjudicated you. By law a judge must adjudicate you guilty of a DUI and may not withhold adjudication. If you have ever been adjudicated guilty of any crime, you cannot have your record expunged. Therefore, you need to look at the judgment and sentence. If for some reason, be it a mistake, youthful offender status, or some sort of diversion program and you got a withheld, you might be able to have your record sealed, but even if FDLE certified you, you might run into resistance from the state when you file your motion. Chances are you were adjudicated guilty, however, and will not qualify for an expunction. You are certainly facing an uphill battle.