When you apply a coupon code programmatically, or when you really need it anyway, you may want to hide the coupon code on the cart page.
This is simply because you want to avoid certain customers who will know the coupon code and try to give it to someone else.
Remove / Rename / Hide Coupon Code from Cart Totals – WooCommerce
add_filter( 'woocommerce_cart_totals_coupon_label', codeamend_hide_coupon_code, 99, 2 );
function codeamend_hide_coupon_code( $label, $coupon ) {
return 'Coupon Applied!';
}
Remove “Have a Coupon?” Form in WooCommerce Checkout Page
remove_action( 'woocommerce_before_checkout_form', 'woocommerce_checkout_coupon_form', 10 );