How can I permanently cancel my Apple TV without having apple renew it every month against my wishes ?

See instructions in How to cancel a subscription from Apple - Apple Support or use the following instructions to cancel on the web: How to cancel Apple TV+ - Apple Support

Both of those link have steps to cancel the subscription. Cancellation is permanent unless you and you alone decide to restart the subscription. There is no way for Apple to automatically re-subscribe you. The system is set up such that, that cannot happen.

Once cancelled, the subscription will not restart unless you and only you restart it.