Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Log into any Microsoft account you may have on this link:
https://account.microsoft.com/services/
Are you able to find your subscription listed there?
If so, click Manage on the subscription, are you able to cancel the subscription or disable the recurring billing on the subscription from there.
If not, what error is indicated when you try to cancel the subscription?