Avast subscription is necessary when you want to buy a plan and get whole services. But the negative point is that Avast automatically cuts the amount from your bank account when the renewal date comes. So, it will be best if you cancel the subscription of Avast, to do that follow these steps:

-Login to your email Id and search for the email came from Avast
when you took Avast subscription.
-Then open that email and click on Cancel Subscription.
-Click on Ok and confirm unsubscribe.

These are the steps, if you are unable to understand the method, then call on Avast phone number customer service and get help.