NOTE: This command has been reported as broken - if it isn't working for you, it's due to a fault in the game, not your own! This command removes the specified state as a 'core' of the specified country. A 'core' is a state that's considered to be a rightful part of a country.
remove_core [state id] [country tag]
|The ID of the state you wish to remove as a core.
|The tag of the country you wish to remove the specified state as a core from.