Removing factions

This is probably a quite easy question, but I'm still a newbie when it comes to edit the text-files in Rome.

How can you remove a faction from the custom-games section? The faction don't have to disappear from the game; its enough that it can't be chosen in a custom battle.

Would be nice with some help ~:)

Sorry for doubleposting, but are there really none here that can tell the answer of the question?

All the factions that are present in the main campaign are also selectable in custom battles.