@SteinVidar 

You generally cannot directly change the email address of an existing TP-Link account; instead, you must create a new TP-Link ID with the desired email address, then unbind your Deco and Tapo devices from the old account, and finally reconfigure them to the new account. Follow the steps for your specific app (Tapo, Deco) to log out of your current account, log in with the new one, and set up your devices again as if they were new. 

However there is a way to switch the owner of your current deco from one email to another see the steps in the post below 

https://www.tp-link.com/us/support/faq/2957/

  @SteinVidar 

Hi, can I have the model number and firmware version of your Deco?

If you want to change the owner ID/email on the Deco APP, you can refer to:

How to change the owner account on Deco APP

Wait for your reply.

Best regards.

@SteinVidar Don't just type the actual email address lol...the internet is a very bad place