Remove Woocommerce shipping option for one particular city - woocommerce

Question

Need some help on this...Please :)
I have this site that is using the Woocommerce's shipping option for "Starken por pagar", that works globally for all cities
And right after that is "Envío Gratis" that is send it for my actual shipping plugin, that calculate free shipping "Envío Gratis" when one particular city is selected.
My idea is that I need to remove "Starken por pagar" when the user select one particular city (one only - the same that is used by my shipping plugin) and left only the "Envío Gratis" for that city.
Because now I dont need the users need to pay for some service that is free. And as you may know, some people barely read the things in front of ther eyes :P
I tried with this (Im not an expert, sorry)
function filter_woocommerce_package_rates( $rates, $package ) {
// Loop trough
foreach ( $rates as $rate_id => $rate ) {
// Checks if a value exists in an array, multiple can be added, separated by a comma
if ( in_array( $rate->method_id, array( 'local_pickup', 'free_shipping' ) ) ) {
unset( $rates['flat_rate:28'] );
}
}
return $rates;
}
add_filter( 'woocommerce_package_rates', 'filter_woocommerce_package_rates', 10, 2 );
Or
// Hide shipping in cart page.
add_filter( 'woocommerce_product_needs_shipping', 'disable_shipping_in_cart_page', 10, 2 );
function disable_shipping_in_cart_page( $needs_shipping, $product ){
if ( is_cart() )
$needs_shipping = false;
return $needs_shipping;
}
// Conditionally remove Flat Rate which qualifies for free shipping
add_filter( 'woocommerce_package_rates', 'hide_flat_rate_when_free_is_available', 10, 3 );
function hide_flat_rate_when_free_is_available( $rates, $package ) {
$free = array();
$free_available = false;
foreach ( $rates as $rate_key => $rate ) {
if ( 'free_shipping' === $rate->method_id ){
$free_available = true;
break;
}
}
foreach ( $rates as $rate_key => $rate ) {
if ( $free_available && 'flat_rate' === $rate->method_id )
unset($rates[$rate_key]);
}
return $rates;
}
Thank you :)