Yes, you have to pay the balance of the fees in your PC 1000 case. If you don't pay the fees, the court will convert them to a civil judgment, which is the same thing as losing a lawsuit.
There is no way to seal the case, but it cannot be used against you.
Penal Code 1000.4(a) says, "Upon successful completion of a deferred entry of judgment program, the arrest upon which the judgment was deferred shall be deemed to have never occurred. The defendant may indicate in response to any question concerning his or her prior criminal record that he or she was not arrested or granted deferred entry of judgment for the offense, except as specified in subdivision (b). A record pertaining to an arrest resulting in successful completion of a deferred entry of judgment program shall not, without the defendant's consent, be used in any way that could result in the denial of any employment, benefit, license, or certificate."
Penal Code 1000.4(b) says you still have to disclose the arrest if you're applying to be a peace officer, which includes police officer, deputy sheriff, probation officer and some other law enforcement jobs.
Most courts will require the payment of any and all fines and fees before dismissing the case, but if they didn't, it will convert to a civil judgment.
As indicated, adult records cannot be "sealed" in California, but the relief under Penal Code section 1000 and the various subsections protect you the best they can from this being used against you or having to be disclosed on applications.
I don't agree with Mr. Dane's response. The law is clear: dismissal in a PC1000 case cannot be conditioned on the payment of fees. You say the dismissal is a done deal. Thus, there was no conviction. So, there is no record to reveal on a questionnaire. But, yes, you are still required to pay the fee, and they will generally accept very small payments.