Some schools will allow students to request an alternate exam date for AP exams while other schools require students to go through the school's testing coordinator to move to the alternate exam date. You can log in to your student account at TotalRegistration.net to see if the Request Alternate Date for Exam link is active in your account (see below screenshot for an example). If it is, click the link and follow the instructions to request an alternate date. Your school's testing coordinator will either approve or deny your request.
If the Request Alternate Date for Exam link is not showing on your student account, then your school did not activate that option and you must contact your school's testing coordinator to request to move your exam date.