We don't have a concept of trial cancellation. Since our trials aren't tied to a payment method (like a credit card), when a trial expires, AuthoredUp will simply stop working. You will not charged.
If you do not wish to use AuthoredUp, you can just log out and uninstall the extension.
If you, however, wish to delete your account and all personal data, please consult this article: https://authoredup.com/help/delete-my-account