Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Log into your Microsoft account on this link, do you find the subscription lsited there.
https://account.microsoft.com/services/
If you find the subscription, you can cancel the subscription using the steps on this link, and also disable the recurring billing on the subscription.
If you pay Microsoft directly for the subscription, you can check your eligibility for a refund using the steps on this link.
I notice you posted to the MacOS forum, if you pay for the subscription through the Apple Store, you will need to contact Apple Support to arrange the refund: https://support.apple.com/118428