Avast cannot remove the managera add-on, and I have followed all of the steps outlined in this thread https://forum.avast.com/index.php?topic=53253.0
Attached are the logs needed. Please help!
hey and welcome to the forum. could you also do a malwarebyte scan an attach that log please seense it also in the guide you followed 
second does avast gives a popup if so plasese attach a picthure of that,it will give the malware expert how will help you some more information.
thanks
Resetting the browser will remove this. Which browser is it in ?