groupname:
    default: **TRUE**
    permissions:
- -factions.kit.fullplayer (this "stops" players using all faction based)
- +factions.kit.halfplayer (but this give them perms to do every command except the create faction)

or more simply


  groupname:
    default: **TRUE**
    permissions:
- -factions.create (which takes away the perm to make one)