How to Hide Other WooCommerce Shipping Methods if Free Shipping is available
This feature is used to hide other flat rate shipping methods once free shipping is available.
This option is available in the Settings -> General Settings.
In the screenshots below, you can check the option settings and their output.
On the checkout page, once the free shipping is eligible, it will hide other shipping methods.
For example:
If the order total is above $300, free shipping becomes available. As soon as the customer adds enough items to reach that amount, WooCommerce will display only free shipping and hide all other shipping methods.