Turn off the "add account" button in new outlook

Anyway of doing this, it adds it to the main account and not a secondary account. I know theres a convert button and the option to add it in the settings, but its just so front and centre users ignore training. Its costing us so much time for users to move the sent mails after we fix it. And no, moving back to old outlook isnt an option due to the bad cache and memory management.