California courts do not have jurisdiction over a New York case.
You should contact a New York attorney. You may also want to post your question in the New York section of Avvo.
You might also call the court and ask if there is a way to clear it up. If it's a simple infraction, you might just be able to pay a fine; however, DUI offenses are usually misdemeanors.
California law allows a lawyer to appear on the client's behalf in most misdemeanor matters. A New York criminal defense attorney could tell you if there are similar provisions in New York law.
Failing to handle the New York DUI could also lead to a drivers license suspension, even in California.