The short answer is: maybe. A so-called "expungement" will NOT terminate your duty to register as a sex offender.

Under Penal Code §1203.4, a person who is granted probation can apply to have the case dismissed after probation is complete. This is sometimes called an expungement, but it doesn't really expunge anything or seal your record. The conviction is still a part of the court's public records, which will also show the case was dismissed. You still must disclose the conviction when applying to be a police officer or for certain other jobs, or if asked on an application for a state license or to run for public office. It will not remove any restrictions on your right to own a firearm or relieve you of the requirement to register as a sex offender. The conviction can still be considered a prior offense; for instance, a prior theft conviction could make any future petty theft a felony, or a prior DUI conviction could be used to increase the punishment in subsequent DUI convictions.

Penal Code §288a is oral sex with a minor. A violation of subsection (c), oral sex with a child under the age of 14, cannot be dismissed under §1203.4, but other subsections can.

It may be possible to terminate sex offender registration through a different legal prodeeding. You should consult an attorney familiar with sex offender registration statutes.

PC 288, 288a(c), and 288.5 are specifically NOT capable of expungement. IF that is you, forget it. Other 288 sections might be expunged, but I would not offer an guarantee of success. Even if successful, you'd still have to separately petition the court for removal from registration status, and I would rate that even less likely to succeed. You'd need quite compelling good cause and proof of dramatic life change to even justify trying. Just because 'you wanna' and registration causes you serious problems is not good cause. It is intended to cause you serious problems; forever. However, if you think you qualify, and have good cause, feel free to contact me if serious about pursuing.