I think i could not make the question more explicit than what is in the title; on the content editor, you can click on the flag item and add a new language version, but no idea how to remove one
on the versions ribbon, you can remove a version number, but it doesn't seem to allow you to pick a single language of the current version for removal
Select 'Versions' in a ribbon tag. Switch 'Language' to the language you want to remove version from. Click 'Remove' in the 'Versions' commands group.
It will remove only the current version from the chosen language - it will NOT remove version from any other language.