The first step in
removing the Avast email signature is to uncheck the box. Click on the Settings icon in the system tray, and then select Privacy. Scroll down to Mail Shield and click the 'Edit' button. To remove the signature, uncheck the option and save your changes. If you have the email client installed on your PC, you can uncheck the box by double-clicking on the Avast Antivirus Software icon in the system tray.
See also -
https://www.folkspaper.com/topic/why-is-...1376.html#