Removing Avast Email signature

How to Remove the Avast email signature from both web based emails and Outlook... even when
the mail scanning option is not installed.

It's a bug but you'll need to install the mail scanning option, then uncheck the mail signature text options and then turn off email scanning.  Details in the posting below.

How to Remove/Disable/Turn Off Avast E-mail Footer Signature

If you are using any Avast Antivirus, including the free version and some of the major desktop e-mail clients (Microsoft Outlook, Mozilla Thunderbird, Zimbra Desktop, eM Client, Inky, Claws Mail), Avast automatically inserts e-mail footer signature into all your clean outgoing messages.

Here's additional info with the specific steps: