Filter out WooCommerce Shipment unused tracking services

wc_shipment_tracking_get_providers.php

add_filter( 'wc_shipment_tracking_get_providers', 'custom_shipment_tracking' );

function custom_shipment_tracking( $providers ) {
  
    unset($providers['Global']);

	unset($providers['Australia']);
    unset($providers['Austria']);
    unset($providers['Brazil']);
    unset($providers['Belgium']);
    unset($providers['Canada']);
    unset($providers['Czech Republic']);
    unset($providers['Finland']);
    unset($providers['France']);
    unset($providers['Germany']);
    unset($providers['Ireland']);
    unset($providers['Italy']);
    unset($providers['India']);
    unset($providers['Netherlands']);
    unset($providers['New Zealand']);
    unset($providers['Poland']);
    unset($providers['Romania']);
    unset($providers['South African']);
    unset($providers['Sweden']);
    unset($providers['United Kingdom']);
    // unset($providers['United States']); // Keeps United States
    unset($providers['United States']['DHL eCommerce']);
	unset($providers['United States']['Fedex']);
  	unset($providers['United States']['FedEx Sameday']);
  	unset($providers['United States']['GlobalPost']);
  	//unset($providers['United States']['UPS']); // Keeps UPS
  	unset($providers['United States']['USPS']);
  	unset($providers['United States']['OnTrac']);
  	unset($providers['United States']['DHL US']);

    return $providers;
}

add_filter( 'woocommerce_shipment_tracking_default_provider', 'custom_woocommerce_shipment_tracking_default_provider' );
function custom_woocommerce_shipment_tracking_default_provider( $provider ) {
	$provider = 'UPS'; 
	return $provider;
}