Marketplace uses Micro Focus Access manager for user accounts. If you need more information about what kind of Marketplace account you have, please refer to this Marketplace login help article.
Information like name and email address are managed in Access Manager.
To update your account information for an Access Manager account, use this link.
To update your account information for a Control Tower account, use this link. Please note Control Tower accounts do not allow you to change your email address once the account is created.