If it's expired. it means it's over. There's nothing left to cancel. It has ended, and is completely inactive now.
If your subscription was unable to be charged for any reason, and it expired because of that, you are still responsible for the pending payment. The pending charge puts your account in bad standing and prevents you from accessing other iTunes or App Store services such as Updating apps.
You must add a verifiable payment method to your account to complete the pending charge. Once it's completed successfully, you can then access the other App Store services such as updating apps.
click here ➜ Add a payment method to your Apple ID - Apple Support
You can request a refund for the charge once its completed by clicking here ➜ Contact Apple Support for a refund for a cancelled subscription