A family of Microsoft word processing software products for creating web, email, and print documents.
You have to cancel the subscription from your account at https://account.microsoft.com/services . Turn off recurring billing first, if it is currently enabled. See https://support.microsoft.com/en-us/accounts-billing/subscriptions/cancel-a-microsoft-365-subscription .
For more about refunds, have a look at https://support.microsoft.com/accounts-billing/subscriptions/how-to-get-a-refund-on-a-microsoft-subscription.