This company is dogshit. It is impossible to cancel my account. I am on hold for 30 minutes.
What account do you mean? Forum account or your online account that you used to buy avast 2016? Do you have a order number or such? Write it down here and I will report it to the moderators and one of the avast guys will assist you.
Hi noh, welcome to the forum 
Are you calling the Avast Phone support number ? Don’t do that.
Describe your problem here, and we will help you.
Greetz, Red.
You should have read what is on the page with the phone-number.
It clearly tells what they do provide help with and account issues isn’t one of them.
Installing your Avast Configuring your Avast Updating or uninstalling Avast
Deleting your account is really easy.
Login to your account (https://my.avast.com) > click on your name > profile details > delete account