We would be sad to see you go, but we understand that things happen sometimes.
To cancel your Team subscription, just head over to your Teams account page and click the gear icon beside your Team name in the Overview section. You can deactivate your team from here. When your subscription is deactivated, it will no longer renew automatically. That said, your Team will still be able to use any data remaining on the account.
Of course, if you have any more questions or run into any issues, please reach out to our support bears here.