You can change the email address associated with your PC Warframe account from the Account Management Page: www.warframe.com/user.
When you access the page, you will notice an EDIT button next to Email under User Information.
Clicking on this button will walk you through the process of changing your Warframe e-mail. Please be aware that if 2-Factor Authentication (TennoGuard 2FA) is active on your account, you will need to be able to access your current Warframe e-mail.
If you are unable to access your email account to retrieve the 2FA code, please contact Support for assistance.
Since your email address is not collected to create your Console account, this is only available for PC players.