This article explains how to change the email address on your Magento.com account when the field is grayed out.
The email address on your Magento.com account is linked to your Adobe account at https://account.adobe.com and will have to be updated there.
Changing the email address for a user who has their own account at https://account.adobe.com
Send an email to Grp-magento-HelpCenterLoginIssues@adobe.com stating the following:
Request the team to merge both accounts in order to update the email address on the existing account.
Changing the email address for a user who currently does not have their own account at https://account.adobe.com
If you have access to the mailbox of the [current owner email], reset the password for the current owner’s email following the Reset or change your Adobe password guide in the Creative Cloud User Guide.
However, if you don’t have access to emails sent to the [current owner email], follow these steps:
Reset forgotten password in the Creative Cloud User Guide.