Finley from Shopify here! Thanks for posting your question.
Otherwise, updating your EIN and business tax information for your Shopify Payments account is something that will need to be actioned by our billing team.
To get this process started, I've sent an email to your Shopify Community email address. Please respond with your .myshopify.com URL and from there we can send this request to our billing team.
Once our team receives your request, they'll be back in touch to gather any information we need to update these details.