Woocommerce free shipping coupon not working if unset(Hide) free shipping method

I want to hide free shipping options and its working fine but free shipping coupon not working.

function hide_shipping_when_free_is_available($rates)
{
    // Current value of the shopping cart
    $cart_subtotal = WC()->cart->subtotal;
    $currency = get_woocommerce_currency();

    $free = array();

    foreach ($rates as $rate_id => $rate) {
        if ('free_shipping' !== $rate->method_id) {
            $rates[$rate_id]->cost = $rates[$rate_id]->cost;
        } else if ('free_shipping' === $rate->method_id) {
            // Free shipping currency convert to euro and apply 
            //if ($currency != 'USD' && $currency != 'GBP' && $currency != 'CHF') {
            $free_shipping_amounts = get_free_shipping_amounts();
            $min = min((array)$free_shipping_amounts);
            if ($currency != 'USD' && $currency != 'GBP' && $currency != 'CHF') {
                $min = get_exchanged_currency($currency, $min, '', '', '', '', 0);
            }
            $free_shipping    = new \WC_Shipping_Free_Shipping($rate->instance_id);
            $applied_coupons  = WC()->cart->get_applied_coupons();

            if ('either' === $free_shipping->requires && !empty($applied_coupons) && $cart_subtotal < $min) {
                foreach ($applied_coupons as $coupon_code) {
                    $coupon = new WC_Coupon($coupon_code);
                    if ($coupon->get_free_shipping()) {
                        $coupon_free_ship = true;
                        break;
                    }
                }
            }
            if ($cart_subtotal < $min && !isset($coupon_free_ship)) {

                unset($rates[$rate_id]);
                echo "Hello";
            } else {
                if ($currency == 'CHF') {
                    unset($rates[$rate_id]);
                    return $rates;
                }
                $free[$rate_id] = $rate;
                break;
            }
        }
    }
    return !empty($free) ? $free : $rates;
}

add_filter('woocommerce_package_rates', 'hide_shipping_when_free_is_available', 100);

The above code is working fine but I just want to hide free shipping methods. I tried to unset free shipping methods to hide it but free-shipping coupon code not working. coupon code applied but discount not applied.

I appreciate it if someone can help me with this.