无法删除由opencart驱动

I'm new with opencart. I've been trying to remove the powered by Opencart for the past few days.

I've tried changing : admin/language/en-gb/common/footer.php

and changed the last part and now it looks like this unfortunately nothing has changed:

<?php
// Text
$_['text_information']  = 'Information';
$_['text_service']      = 'Customer Service';
$_['text_extra']        = 'Extras';
$_['text_contact']      = 'Contact Us';
$_['text_return']       = 'Returns';
$_['text_sitemap']      = 'Site Map';
$_['text_manufacturer'] = 'Brands';
$_['text_voucher']      = 'Gift Certificates';
$_['text_affiliate']    = 'Affiliates';
$_['text_special']      = 'Specials';
$_['text_account']      = 'My Account';
$_['text_order']        = 'Order History';
$_['text_wishlist']     = 'Wish List';
$_['text_newsletter']   = 'Newsletter';
$_['text_powered']      = '%s &copy; %s';

you go to admin\view\template\common\footer.tpl and delete

Go to for remove the front end powered from website

1.catalog/view/theme/default/template/common/footer.tpl.

2.Comment the part or delete.