Removes unnecessary countries (and their states) from the woocommerce_params that Woocommerce JSON encodes on every Wordpress page.

Remove countries from woocommece_params

add_filter('woocommerce_states',function($countries){

  // list the countries you actually want states for in this array
	$countries_with_states = array( 'US','CA');
	
	foreach($countries as $country=>$states){
		if( !in_array($country, $countries_with_states) ){
			unset( $countries[$country] );
		}
	}
	return $countries;
});