magento2/app/code/Magento/Sales/Controller/Adminhtml/Order/Address.php

<?php
/**
 *
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
namespace Magento\Sales\Controller\Adminhtml\Order;

class Address extends \Magento\Sales\Controller\Adminhtml\Order
{
    /**
     * Authorization level of a basic admin session
     *
     * @see _isAllowed()
     */
    const ADMIN_RESOURCE = 'Magento_Sales::actions_edit';

    /**
     * Edit order address form
     *
     * @return \Magento\Backend\Model\View\Result\Page|\Magento\Backend\Model\View\Result\Redirect
     */
    public function execute()
    {
        $addressId = $this->getRequest()->getParam('address_id');
        $address = $this->_objectManager->create(\Magento\Sales\Model\Order\Address::class)->load($addressId);
        if ($address->getId()) {
            $this->_coreRegistry->register('order_address', $address);
            $resultPage = $this->resultPageFactory->create();
            // Do not display VAT validation button on edit order address form
            $addressFormContainer = $resultPage->getLayout()->getBlock('sales_order_address.form.container');
            if ($addressFormContainer) {
                $addressFormContainer->getChildBlock('form')->setDisplayVatValidationButton(false);
            }

            return $resultPage;
        } else {
            return $this->resultRedirectFactory->create()->setPath('sales/*/');
        }
    }
}