Hide shipping rates when free shipping is available

dokan-free-shipping-hide.php

/**
 * Hide shipping rates when free shipping is available.
 *
 * @param array $rates Array of rates found for the package.
 * @return array
 */
function dokan_vendor_shipping_hide_when_free_is_available( $rates ) {
    $free = array();
    foreach ( $rates as $rate_id => $rate ) {
        if ( 'free_shipping' === $rate->method_id || 'free_shipping' === $rate->id || strpos( $rate->id, 'free_shipping' ) !== false ) {
            $free[ $rate_id ] = $rate;
            break;
        }
    }
    return ! empty( $free ) ? $free : $rates;
}
add_filter( 'woocommerce_package_rates', 'dokan_vendor_shipping_hide_when_free_is_available', 100 );