When an app is being uninstalled, we delete it from the Privacy Advisor database, so it shouldn't be listed any more. If we by any chance didn't see the uninstallation of some app, I'm afraid there is no such way of removing it from the Privacy Advisor, or to clean the whole (and only) Privacy Advisor database.
What you can do is delete all the data of avast! Mobile Security, but by doing that you will lose all your settings. To do it just go to System settings - Apps - avast! Mobile Security and click the "Clear data" button.