Found this: https://answers.ea.com/t5/Technical-Issues/Unlink-account/td-p/7462087

To unlink your Nintendo switch from your Origin account you'll need to speak to a Game Advisor.

You can contact support by following the steps below: Click on the following link: https://help.ea.com/contact-us Make sure you are logged in (top right corner) Click on the blue button "Contact a Game Advisor" Enter the name of your game or product (or "Origin" for account-related issues) and click "Find Solutions" Select the type of issue and the platform you play on, and click on "Find Solutions". Click on the blue button "I still need help" if the FAQ articles do not apply to your situation. Select a contact option. Note that you may get different contact options depending on your country.