Personally, I wouldn't worry about it. If you reall need to remove it, then I'd suggest using a razor blade or other scraping tool. Using chemicals on your hard drive MIGHT not be the best idea, since metals tend to leach chemicals into themselves and then release them when heated. Releasing any kind of chemical into the inside of the drive, not that it would, but it could be a problem and might affect the drive. I'd just scrape it off or leave it and call it a day.
If that's a plastic enclosure, you certainly don't want to use a harsh chemical like acetone. It will almost certainly eat the plastic.