How to remove a faction?

Ok, i need to know how to either remove a faction or make it unplayable. I just need it for custom battles right now. I need to get rid of the English, the Almohad, and all those little minor factions. It for VI, I'm currently converting the High Period.

Any help would be much appreciated.

Remove any and all mention of the faction from the Early/High/Late era files EXCEPT for DeclareFaction:: at the very top.

EDIT: That is for campaigns. For custom battles, do the same thing, but also go into the Gnome editor and open the Unit_prod file and scroll over until you find the very last column. Remove any mention of the faction from this column and save.