Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
If you have a Microsoft 365 subscription on your personal Microsoft account and you want to cancel the subscription, log into your personal Microsoft account on this link.
https://account.microsoft.com/services/
Then, select the Microsoft 365 subscription and click Manage.
From there, you can cancel the subscription and also disable the recurring billing on the subscription.
You should then be entitled to a pro-rata refund, you can check your eligibility to a refund using the steps on this link.