How to remove avast! icon from browser

With the last update an avast! icon is now showing in my Firefox navigation toolbar. I don’t have the navigation toolbar showing usually, so it ends up being just the avast! icon and nothing else taking up an entire bar. If I remove the icon and toolbar, they show up again when I restart my browser or open a new window. How can I permanently remove this icon?

Try disabling it in the firefox add-ons.

Because it is enabled it will automatically open the toolbar to be able to run, so you have to disable it.