No need to cancel your own account. TurboTax accounts cannot be cancelled. You can abandon it and not use it any more since you are now using your spouse's account for joint returns. Keep a record of how to access your old account in case you need to get to an old return someday---they are saved for seven years. But as for any emails about filing, ignore those--you know that you filed, and you can just ignore those emails like you ignore any other spam.