Checkout the content-single-product.php WooCommerce template for an idea of what functions are hooked where. It is very well commented. When you learn about hooks and filters, all these questions start to become similar.
You'll want to remove the function from it's current hook and add it to a new hook. This sample includes a fake hook destination because I don't know what theme you are using and all themes are different. This is for your functions.php or your child theme's functions.php:
remove_acton( 'woocommerce_single_product_summary', 'woocommerce_template_single_excerpt', 20 );
add_action( 'your_theme_some_hook', 'woocommerce_template_single_excerpt' );
add_action( 'woocommerce_before_single_product', 'wpa116854_move_product_excerpt' );
your_theme_some_hook with the appropriate hook. Or you can add the
woocommerce_template_single_excerpt() function directly to your
Something I wrote a while ago to explain how to manipulate WordPress functions and action hooks.