How to use Replace/Enable Email feature?
By default, Replace Email is active. It means that after creating template WooCommerce will use those email templates.
If you want to disable it for a while you can turn off it. For example, you have a live website, in this case you can turn off replace email feature, when your website email template will ready just enable it and enjoy your emails.
This feature located in the settings tab -> general settings section .
You have 2 choice:
1. Enable/disable specific email type. For doing it you need select email type from dropdown then navigate to settings.
2. Enable/disable all email types at once. For doing it you need just navigate to settings.