您可以使用轻量级的SQL查询来获取客户的总购买金额，并使用该查询来隐藏“我的账户订单”部分，如果总购买金额等于0（零）：

// 获取客户购买总金额
function get_customer_purchases_total_amount(){
    global $wpdb;

    return (float) $$wpdb->get_var( $wpdb->prepare( "
        SELECT SUM(pm.meta_value)
        FROM {$wpdb->prefix}posts as p
        INNER JOIN {$wpdb->prefix}postmeta as pm ON p.ID = pm.post_id
        INNER JOIN {$wpdb->prefix}postmeta as pm2 ON p.ID = pm2.post_id
        WHERE p.post_type = 'shop_order'
        AND p.post_status IN ('wc-processing','wc-completed')
        AND pm.meta_key = '_order_total'
        AND pm2.meta_key = '_customer_user'
        AND pm2.meta_value = %d
    ", get_current_user_id() ) );
}

// 有条件地隐藏“我的账户订单”部分
add_filter( 'woocommerce_account_menu_items', 'hide_customer_account_orders_conditionally', 100, 1 );
function hide_customer_account_orders_conditionally( $items ) {
    if ( get_customer_purchases_total_amount() == 0 ) {
        unset( $items['orders'] );
    }
    return $items;
}

将代码放在您的子主题的functions.php文件中（或插件中）。已测试并可正常运行。