First, I’m an Avast user and not an Avast Team member.
Cancelling automatic renewal of the Avast subscription
- See https://support.avast.com/article/account-unsubscribe/#pc or https://support.avast.com/article/35 ,use the primary link for advice. Also see https://support.avast.com/article/Unsubscribe-FAQ/#pc
You could switch back to Avast free at the end of your subscription, it has been fine for me in the many years I have used it. But you must ensure you have cancelled the auto payment renewal.