I am not sure if you are now over 18 or not. Once you are 18 your juvenile record will be sealed. It appears that you were arrested when you were 11 but never prosecuted for the crime. I assume you mean that the arrest record is still on your record. That will go away when your juvey record is sealed.
How do you know it's on your record? The best bet is to check with the LA County District Attorney's Office - call the office and tell the receptionist you'd like to find out whether there is any record of you in their data system -- fi there is, ask what the disposition was. That will tell you whether you have a conviction for anything. If so, juvenile records are private and not subject to disclosure other than to law enforcement agencies. Good Luck!
one answer is that the probation department didn't feel you warranted having to go to court and nothing will happen. If you don't get a letter from the court than you don't have a coiurt record. otherwise you or your parent can go to the D.A.'s office and ask if they have any paperwork on you and show them the citation the police gave you (they did give you a citation, didn't they?) If no citation, I think you can safely ignore going back to court. they did give you a citation, didn't they?