I have found a solution to the problem for those users who still have that irritating thing sitting in the status bar.
1. Type about:config in the address bar [enter].
2. Make a filter for update.app
3. Right click and reset each of the entries that are bold back to the defaults (update.app.AppDescription, update.app.updateURL, update.app.Version, and
update.app.UpdatesAvailable)
4. Restart Mozilla Firefox