Last name update in AWS Certification

You would ideally see the instructions in the exam confirmation email from the provider you are taking the test with. I have pasted the steps I received during the latest test I took 2 weeks ago. Hope this helps.

To correct your first name(s) and/or last name(s), please follow the steps below immediately:

1. Click here to submit a ticket for AWS Support
2. Complete all required fields in the form
3. In the Inquiry Type * field, select "Account Assistance"
4. In the Additional Details * field, select "Name Change"
5. In the How can we help you? * field, please ask us to change your name, then enter your name as it is listed on your valid forms of identification.
6. Click the Submit button

It might take 2 or more days to get the name updated. I would advice you to reschedule the exam to avoid any issues.