<?php
/**
 * Copyright © 2016 Magento. All rights reserved.
 * See COPYING.txt for license details.
 */

$objectManager = \Magento\TestFramework\Helper\Bootstrap::getObjectManager();
/** @var \Magento\Framework\Registry $registry */
$registry = $objectManager->get('Magento\Framework\Registry');

$registry->unregister('isSecureArea');
$registry->register('isSecureArea', true);

//Remove categories
/** @var Magento\Catalog\Model\ResourceModel\Category\Collection $collection */
$collection = $objectManager->create('Magento\Catalog\Model\ResourceModel\Category\Collection');
$collection
    ->addAttributeToFilter('level', 2)
    ->load()
    ->delete();

$registry->unregister('isSecureArea');
$registry->register('isSecureArea', false);
