You can change the email address associated with your PC Warframe account on the www.warframe.com/user page.
When you access the page you will notice an option under Account Management, CHANGE EMAIL:
Clicking on this button will take you through the process to change your Warframe e-mail. Please be aware that if 2-Factor Authentication (2FA) active on your account, you will require access to your current Warframe e-mail in order to link your new e-mail to your account.
Since we don't get emails from Console accounts on creation, this is a PC only Account Management Tool.