add_filter('woocommerce_checkout_fields', 'default_values_checkout_fields');
function default_values_checkout_fields($fields) {
  if (!is_user_logged_in()) {
      unset($fields['billing_city']);
      unset($fields['billing_first_name']);
      unset($fields['billing_last_name']);
      unset($fields['billing_company']);
      unset($fields['billing_address_1']);
      unset($fields['billing_address_2']);
      unset($fields['billing_city']);
      unset($fields['billing_postcode']);
      unset($fields['billing_country']);
      unset($fields['billing_state']);
      unset($fields['billing_email']);
      unset($fields['billing_phone']);
      unset($fields['shipping_city']);
      unset($fields['shipping_first_name']);
      unset($fields['shipping_last_name']);
      unset($fields['shipping_company']);
      unset($fields['shipping_address_1']);
      unset($fields['shipping_address_2']);
      unset($fields['shipping_postcode']);
      unset($fields['shipping_country']);
      unset($fields['shipping_state']);
      return $fields;
  }
}

add_filter('woocommerce_checkout_get_value','__return_empty_string', 1, 1);