Code to disable the assembly cost option provided by Product Assembly / Gift Wrap / Plugin - By WebToffee (WebToffee WooCommerce Gift Cards)

function.php

<?php //Do not copy this line of code
function wt_admin_show_assembly_cost_on_giftcard() {

        ?>
        <script>
            jQuery(document).ready(function() { 
                setTimeout(function() {
                    if(jQuery('._wt_gc_amounts_field').length){
                        jQuery('._has_assembly_field').insertAfter('._wt_gc_amounts_field');
                        jQuery('._disable_assembly_field').insertAfter('._wt_gc_amounts_field');
                        jQuery('._assembly_cost_field').insertAfter('._wt_gc_amounts_field');
                        jQuery('._has_assembly_field ._assembly_cost_field ._disable_assembly_field').show();
                    }
                }, 3000);
            });
        </script>

        <?php
}

add_action('admin_footer', 'wt_admin_show_assembly_cost_on_giftcard');