I am getting charged subscription fee monthly from an outlook account I have forgotten the email to

There is no sub for an outlook email account, there is a sub for an o365 subscription

https://support.microsoft.com/en-us/account-billing/help-with-the-microsoft-account-recovery-form-b19c02d1-a782-dee6-93c3-dc8113b20c42

And

https://support.microsoft.com/en-gb/account-billing/how-to-investigate-a-billing-charge-from-microsoft-398c5328-364c-d5e4-ea8f-f5ad60562a93

This forum is just a user to user forum, no-one here has any account access, try using this method to contact their support to get a refund.

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