There are 7 major steps to cancel this how to cancel avast auto renewal
Sign in to your Avast Account using the link below
Select the My Subscriptions tile.
Locate the Avast subscription that you want to cancel.
Click Unsubscribe under the subscription that you want to cancel.
Optionally let us know why you are unsubscribing, then click Unsubscribe.
Review the details about your canceled subscription, then click Close.