Bethel, Judge. Michael Ashley petitioned the superior court for a writ of mandamus to compel Meria Carstarphen, in her official capacity as Superintendent of Atlanta Public Schools (APS),[1] to hold a due process hearing regarding the non-renewal of his employment contract as a public school administrator pursuant to the Fair Dismissal Act.[2] Carstarphen moved to dismiss the petition arguing that, because Ashley voluntarily retired through the Teachers Retirement System of Georgia (TRS), he was no longer an employee of APS, and therefore no longer eligible for a due process hearing. The superior court granted the motion, finding that Ashley did not have a clear legal right to have any act performed by Carstarphen in her official capacity with APS in regard to the renewal of Ashley’s contract. On appeal, we are asked to determine whether the trial court erred in finding that Ashley effectively waived his right to a due process hearing when he voluntarily filed for retirement and began receiving retirement benefits through TRS. We agree with the trial court that Ashley’s voluntary retirement waived his right to a due process hearing and therefore affirm.“A motion to dismiss may be granted only where a complaint shows with certainty that the plaintiff would not be entitled to relief under any state of facts that could be proven in support of his claim.” Alcatraz Media, LLC v. Yahoo! Inc., 290 Ga. App. 882, 882 (660 SE2d 797) (2008). “We apply a de novo standard of review to the trial court’s grant of a motion to dismiss.” Id. So viewed, the record shows that Ashley was employed with APS for over 30 years. During the 2015 – 2016 academic year, Ashley worked as an assistant principal at an APS middle school. On May 6, 2016, APS sent a letter to Ashley informing him that APS was recommending to the Atlanta Board of Education (the Board) that his employment contract not be renewed for the 2016 – 2017 academic year because his current position was being abolished. The letter went on to inform Ashley that his employment contract with APS would end June 30, 2016, but that he was eligible for re-hire. The letter also stated that Ashley was entitled to certain procedural safeguards before he could be demoted or dismissed from APS, which included a right to a due process hearing. Pursuant to OCGA §§ 20-2-940 and 20-2-942 (b) (1), Ashley timely submitted a request for a due process hearing to challenge the non-renewal of his employment contract with APS.[3] The hearing, originally scheduled for June 28, 2016, was continued to July 27, 2016, and continued again pending settlement discussions. On or about July 13, 2016, Ashley submitted an online application to file for retirement with TRS, listing July 1, 2016, as the effective date of his retirement. That same day, Ashley logged on to the APS portal, completed two required steps, and retired from APS. While settlement negotiations were pending, APS notified Ashley on September 9, 2016, that it had learned of his retirement from TRS, effective July 1, 2016. In an email exchange between attorneys for the parties, APS explained that due to Ashley’s retirement, APS would no longer continue settlement discussions or proceed with the due process hearing regarding the non-renewal of his employment contract.Ashley then filed a verified petition for mandamus asking the superior court to compel Carstarphen to hold the due process hearing. Carstarphen filed a motion to dismiss the petition, which was granted following a hearing. This appeal followed.In his sole enumeration, Ashley argues that his retirement through TRS did not waive his right to a due process hearing, and thus the trial court erred in dismissing his petition for mandamus. We disagree.Mandamus is an extraordinary remedy to compel a public officer to perform a required duty when there is no other adequate legal remedy. It is a discretionary remedy that courts may grant only when the petitioner has a clear legal right to the relief sought[.] . . . In general, mandamus relief is not available to compel officials to follow a general course of conduct, perform a discretionary act, or undo a past act.