Can a defendant withdraw their plea of guilty or nolo contendere and enter a plea of not guilty?

an honest and upright life and has conformed to and obeyed the laws of the land, be permitted by the court to withdraw his or her plea of guilty or nolo contendere and enter a plea of not guilty . . . and . . . the court shall thereupon dismiss the accusatory pleading against the defendant . . . ." The discretionary expungement provision of section 1203.4a, subdivision (b) states: "If a defendant does not satisfy all the requirements of subdivision (a), after a lapse of one year from the date of pronouncement of judgment, a court, in its discretion and in the interests of justice, may grant the relief available pursuant to subdivision (a) . . . if [defendant] has fully complied with and performed the sentence of the court, is not then serving a sentence for any offense, and is not under charge of commission of any crime." A defendant who later has his felony conviction reduced to a misdemeanor is eligible for relief pursuant to section 1203.4a. (People v. Khamvongsa (2017) 8 Cal.App.5th 1239, 1244-1245 [reclassified drug conviction is a misdemeanor for all purposes, including expungement relief pursuant to section 1203.4a].)