Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
1
Try using the steps provided on this link to recover the Microsoft account used for the Microsoft 365 subscription, if that is successful, you can then cancel the subscription.
2
If that process is not successful, you cannot cancel the subscription yourself, the best option is to contact your bank to cancel the direct debit payment on your account for the subscription.
3
If that is not possible, 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