WooCommerce by default provides an option to disable complete orders email notification. Here is where you can find the setting. Configuring ...
Completed — Order fulfilled and complete – requires no further action.
I understand you've noticed that “Order Completed” email is sent twice to your customers.
products, without requiring that these products also be marked Downloadable
WooCommerce allows users to send customized order emails and
(think of this as a status “between” Processing and Completed), you can mark it as such .
when you mark the order as Completed , the completed order email that is sent out
you can unhook the email action by placing this code in your functions.php: remove_action( ...
Mark this order as complete and send tracking info to the customer
Status Control can automatically mark paid orders as 'complete' instead of ...