Regarding cancellation of aws exam

According to the AWS certification FAQ, you can cancel or reschedule your exam up to 24 hours before your scheduled appointment without additional fees.

Yes. You can cancel or reschedule your exam up to 24 hours before your scheduled appointment without additional fees. To reschedule or cancel your exam, go to your AWS Certification Account and click the Manage Pearson VUE exams button. Select the scheduled exam you wish to manage from the Upcoming Appointments menu. Once you reach the 24-hour window before your scheduled appointment, you will not be able to cancel or reschedule your exam. If you miss your scheduled exam appointment, you will forfeit the exam fee and are not eligible for a refund (see medical exception below). You will not be able to register again for the exam until 24 hours after your missed exam time. Missing the exam does not result in a “fail” status.