To disable the Avast email signature, go to the Avast user interface. You can either double-click the Avast icon in the system tray or open the Avast user interface. If you prefer to use the old-fashioned method, select the Avast icon and click on the 'Edit' button. The Avast icon will now be removed. Then, you can go to your settings and click on the 'Disable' button.