By default, firefox on Linux has a long list of language packs installed as Extensions. As a normal user you can’t remove these, while it’s not a big problem, it is an inconvenience. The solution is rather simple as it turns out, if you start firefox as root, you can remove the extensions. Thanks to this thread (new window) for the solution.

So, open a terminal, type “su -” and hit enter, provide your root password and hit enter, then type “firefox” hit enter and wait for firefox to open. Uninstall, close firefox, and you’re done. Simple as that!