Legal Question in Criminal Law in California

yes depending on the facts such as ineffective assistance of counsel, duress, fraud, etc.

Probably not. All you have told us is that your father wishes he had entered a different plea. He will need a better reason than that to persuade the court to let him withdraw his plea.

Your question doesn't really tell us much about why your father wants to change his plea or what he thinks the PD did wrong. He might have good cause to withdraw his plea; I just don't have enough information.

Note that there are deadlines which your father must meet. You haven't told us when he entered his plea, so I can't say when the deadlines will be or whether they have already passed.