Code to remove the fee name from the invoice pdf - By WebToffee

function.php

<?php //Do not copy this line of code
add_filter('wf_pklist_alter_find_replace', 'wt_pklist_alter_total_fee', 10, 6);
function wt_pklist_alter_total_fee($find_replace, $template_type, $order, $box_packing, $order_package, $html) {
    if ('invoice' === $template_type && !empty($order)) {
        if (is_object($order)) {
            $order_id = method_exists($order, 'get_id') ? $order->get_id() : $order->id;
            $user_currency = get_post_meta($order_id, '_order_currency', true);
            $fee_details = $order->get_items('fee');

            if (!empty($fee_details)) {
                $total_fee = 0;

                foreach ($fee_details as $fee_detail) {
                    $total_fee += $fee_detail->get_total();
                }

                $find_replace['[wfte_product_table_fee]'] = wc_price($total_fee, array('currency' => $user_currency));
            }
        }
    }

    return $find_replace;
}