Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Do you see an error message when you try to cancel the subscription?
Note that if you can't find the subscription when you sign in at https://account.microsoft.com/services with your usual e-mail, try signing in with other credentials, typically @outlook.com or @hotmail.com mail addresses. With a bit of luck, you will find the correct account.
For more troubleshooting, see https://support.microsoft.com/en-us/account-billing/how-to-investigate-a-billing-charge-from-microsoft-398c5328-364c-d5e4-ea8f-f5ad60562a93 .