title: Unset specific billing state (county) when country is GB/UK on woocommerce checkout page
body: <p>I'm looking for a way to remove specific billing_state fields.
  For UK/ GB or switzerland for example.</p>
  
  <p>I tried this but this isn't working:</p>
  
  <pre><code>function mp_change_locale_field_defaults($countries) {
      $countries['GB']['state']['hidden'] = true;
      return $countries;
  }
  </code></pre>
  
  <p>The problem is, I cannot remove the billing state once and for all because it is relevant for other countries. 
  So I cannot use</p>
  
  <pre><code>add_filter('woocommerce_billing_fields','simple_remove_billing_fields');
      function simple_remove_billing_fields( $fields = array() ) {
      unset($fields['billing_state']);
      return $fields;
  }
  </code></pre>
  
  <p>I looked into class-wc-countries.php as well but I also did not find the line where I can manually edit this.</p>
  
  <p>Help is very much appreciated.</p>