ROOT account change e-mail?

When you create an AWS account, you provide an email address and password. These are the credentials for the AWS account root user. If you aren't sure of the email address associated with your AWS account, search for messages sent from @signin.aws or @verify.signin.aws to any email address for your organization that might have been used to open the AWS account.

If you know the email address but no longer have access to the email, first try to recover access to the email using one of the following options:

If you own the domain for the email address, you can restore a deleted email address. Alternatively, you can set up a catch-all for your email account, which "catches all" messages sent to email addresses that no longer exist in the mail server and redirects them to another email address.

If the email address on the account is part of your corporate email system, we recommend that you contact your IT system administrators. They might be able to help you regain access to the email.

If you're still not able to sign in to your AWS account, you can find alternate support options at https://aws.amazon.com/contact-us/

SOURCE: https://docs.aws.amazon.com/IAM/latest/UserGuide/troubleshooting_root-user.html