You just need to go into your Mendix Account and use the Merge Account option to merge your accounts and take your certification over to your new account.
https://docs.mendix.com/developerportal/community-tools/mendix-profile/#1011-merging-profiles
I hope this helps!
You can merge your account with your new email address account.
See: https://forum.mendix.com/link/space/app-development/questions/110719