wc-show-free-shipping-for-states-not-on-the-exclusion-list.php

/**
 * Hide ALL shipping options when free shipping is available and customer is NOT in certain states.
 *
 * Change $excluded_states = array( 'AK','HI','GU','PR' ); to include all the states that DO NOT have free shipping.
 */
function wb_hide_all_shipping_when_free_is_available( $rates, $package ) {

	$excluded_states = array( 'AK', 'HI', 'GU', 'PR' );
	if ( isset( $rates['free_shipping'] ) and ! in_array( WC()->customer->shipping_state, $excluded_states ) ) :
		// Get Free Shipping array into a new array.
		$freeshipping = array();
		$freeshipping = $rates['free_shipping'];

		// Empty the $available_methods array.
		unset( $rates );

		// Add Free Shipping back into $avaialble_methods.
		$rates   = array();
		$rates[] = $freeshipping;

	endif;

	if ( isset( $rates['free_shipping'] ) and in_array( WC()->customer->shipping_state, $excluded_states ) ) {

		// remove free shipping option.
		unset( $rates['free_shipping'] );

	}

	return $rates;
}
add_filter( 'woocommerce_package_rates', 'wb_hide_all_shipping_when_free_is_available', 10, 2 );