Only the admin can cancel Business subscriptions. Please log into the web app and go to Settings → Team Management. At the bottom of the page you can click 'Unsubscribe from Any.do for business'. Please note that you will still be able to enjoy Premium features until the original subscription expires (the day the next payment should be made), but you won't be charged.
[** If you are using our Beta Web app please revert back to the official version to perform this action]