My ex rokupay is still on my TV and I have looked all over the site and my TV so I can change it but I can't. I can change the card on file but that's it and I don't have his pin so just stuck!
Is the Roku account yours or your ex's? Using the email address that's displayed on your TV under Settings->System->About can you log in at https://my.roku.com ?
If it's not linked to your account and it's not your payment method, you may just want to factory reset the device, create your own Roku account, and link the device to your new account.