I installed the latest version of LO and found this option was missing. I even installed the suite again only to double check I haven't missed the option during setup. It's not there.
The extra language removal option didn't work perfectly (it would always leave 5 dictionaries intact instead of just 2), but still it did some job. Now I have to remove the dictionaries folders manually and I guess lots of language stuff still exist in other parts of the suite (like UI, for example).