Can’t cancel the Apple Music subscription, whatever in Apple Music application or in setting of my phone.

It has already been cancelled. You can continue to use it until the Dec 6 expiration date. It will not renew.

If the option to cancel a subscription is missing, see the following excerpt from Apple Support article If you want to cancel a subscription from Apple - Apple Support

You might need to scroll down to find the Cancel Subscription button. If there is no Cancel button or you see an expiration message in red text, the subscription is already canceled.