Remove ootb languages in hybris 6.6

How can I get rid of the languages like es, es_CO, ja, cs, etc so that they wont be displayed in the backoffice for localized attributes (see screenshot)

I only want the languages de, en, it, fr, en_GB and en_US.

I already tried to set the property lang.packs=en,de,it,fr,en_GB,en_US in the local.properties. But then a lot of initialization erros occur in files like: /impex/essentialdata-coredefinitions_cs.impex (ruleengine) since they depend on that languages.

What can I do to get rid of the superfluous languages?