If this occurred when you were a minor, it should already be sealed and not public information.
Disclaimer: I am not offering legal advice, assume I do not know the law in your state and that I am just making suggestions for starting points for when you do speak with an attorney. Do NOT rely on anything I write and contact a lawyer in your area immediately after reading my posting.
In most states, if your case occured when you were a minor and it was "deferred" and later dismissed, then it should not appear on your criminal record. If it is still in your "history" then you should contact a lawyer in your hometown and have him pull your file with court permission and investigate what they file it still in your history.
Check with a local lawyer as to whether your case was resolved in a manner that should mean that it should not be part of your record.
Best of luck.
Disclaimer: This answer is provided as a public service and as a general response to a general question, it is not meant, and should not be relied upon as specific legal advice, nor does it create an attorney-client relationship.
With due respect to the lawyers posting above, in Washington state, a deferral and closing of the case is not necessarily the last step in addressing your criminal history record. Washington State Patrol has taken the position that a deferred sentence can still be considered conviction data because a guilty plea has been entered. As such, Washington State Patrol will maintain a criminal record.
In order to address this matter, you need to seek to have your record sealed. If you meet the statutory requirements you can have the record sealed. Contact an attorney in the area you were convicted for more information. Or you can contact the court Clerk, in the court you were convicted, and ask for the instructions on sealing a juvenile records.