We have got a different way to understand how to turn off pop up blocker on avast. However, you can get a very simple hack to learn step by step mentioned below
Open avast antivirus
Go to menu
Visit settings
Select general
Click notifications.
Check the box next to use silent mode and turn off all pop-ups, alerts and messages.
Hope I have been the best guide to solve and stop avast notifications. Still, if you think that you are being failed in this. Then you must contact our customer support for 24 *7 technical support