function my_theme_enqueue_styles() {
    wp_enqueue_style( 'parent-style', get_template_directory_uri() . '/style.css' );
}
add_action( 'wp_enqueue_scripts', 'my_theme_enqueue_styles' );

add_filter('woocommerce_sale_flash', 'woo_custom_hide_sales_flash');

 function woo_custom_hide_sales_flash()
 {
  return false;
 }