Either you or your probation officer must file a petition under Welfare & Institutions Code Section 781. The petition must be served on the District Attorney (and the probation officer, if she is not the person who filed the petition). The court will hold a hearing and determine if the requirements for sealing the record have been met.
You should contact your probation officer and ask if he or she is willing to file the petition for you. If not, you should contact your defense attorney.
The Juvenile Court clerk or your probation officer has a form in which you request to have your record sealed, you serve a copy to each probation and the District Attorney's office and file with the court.
That being said, you need to meet certain qualifications in order to have the record sealed.
First, you must have completed your probation. Second, sufficient time must have elapsed such that either five years have passed since the offense date, or you must be 18 years or older, whichever comes first.
Certain offenses require you to have completed probation for a year or more, while other offenses are no longer able to be sealed.
For a general explanation of juvenile court procedures, feel free to look at the web address below.
You'll find the rules regarding sealing at section 781 of the Welfare and Institutions Code. The list of offenses that can no longer be sealed are listed in paragraph (b) of section 707 of the Welfare and Institutions Code. If you do have such a mark on your record and you still want your record sealed, speak to an attorney. It may be possible for the attorney to convince the court to modify its original order if the interests of justice suggest it to be appropriate. See Welfare and Institutions Code section 782 (which allows the judge to change orders, sometimes years later -- even after you are no longer on probation -- if the interests of justice demand this).
