Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
1
Open Word.
Go to File - Account.
On that window, you should see the Email address of the Microsoft account used for the Microsoft 365 subscription.
Are you then able to use the steps provided on this link to cancel the Microsoft 365 subscription.
2
If you are still unable to find the Microsoft account associated to the subscription, this forum is just a user to user forum, no-one here has any account access, using any Microsoft account you may have, try using the steps they provide on this link to find out what that payment was for.
Then use the steps they provide on this link to cancel whatever that payment was for and get a refund.