Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
1
Log into any Microsoft account you may have on this link and check if there is an active subscription linked to any of oyur Microsoft accounts.
https://account.microsoft.com/services/
If you find an active subscription, click the Manage button beside the subscription, from there, you can cancel the subscription to get a pro-rata refund, and also ensure you disable the Recurring billing on the subscription to avoid any further charges on the subscription.
2
If you are unable to find an active subscription on any Microsoft account you may have, this forum is just a user to user forum, no-one here has any account access, you will need to contact Microsoft Support directly, try using this method to contact their support.
Go to this link: https://support.microsoft.com/contactus
Select Microsoft 365
Click 'Get Home Support'.
In the box provided, type billing.
Press Enter, then on the next page, scroll down and click 'Sign in to Contact Support'.
Navigate to Microsoft 365 and Office - Manage my Subscription.
Select the 'Chat with support agent in web browser' option