Cancel at any time
An Owner or an Administrator of the organisation can cancel a paid plan from Billing, at any time while the paid period is running.
Refund and cancellation
What happens when you cancel a paid plan, and what is refunded.
The plan runs to the end of the period
After you cancel, the plan stays fully in force until the end of the period you have paid for. On that date the organisation moves to the Free plan.
No refund
Cancelling refunds nothing for the unused part of the period.
The full wording is in section 4.5 of the Terms of Service.