Where do I remove admin order fields (unset doesn't work)

Question

I have built shop based on Woocommerce. In admin order, I need to disable state field. It shows state code, not full name, so it doesn't really matter.

When you enter certain order in admin page, you will get Billing and Shipping colums.

So basically, this snippet should do, but it doesnt. It removes fields in "edit" view.

add_filter( 'woocommerce_admin_billing_fields', 'custom_admin_billing_fields', 1, 1 );
function custom_admin_billing_fields( $billing_fields ) {
   unset($billing_fields['state']);
   return $billing_fields;
}

Edit: Here are the screenshots to better understand my problem

As you can see, there is no "state" field, but number 2 (which is state id) shows.

Answer 1

Maybe try this:

function custom_admin_billing_fields( &$billing_fields ) {
   unset($billing_fields['state']);
}

It's not clear if when the custom_admin_billing_fields function is called if its return is actually captured and used. So it's possible that the return is ignored.

The ampersand (&) in the parameter definition makes that variable "by reference" instead of "by value". This way any changes made to this variable in the function will always be returned and affect the original variable passed.