Remove div element generated automatically from theme [closed]

The content that, as you correctly stated, is generated automatically, is generated by wordpress using template files in your theme.
Wordpress will use one of these files, following a convention called template hyerarchy (so, for example, wordpress will use single.php to display a single post page, or archive.php to display an archive page).

To promote the use of reusable chunks of code, you can call, from within this files, other parts that will be incorporated. Two frequent functions used to do this are get_header() and get_footer() that will include respectively header.php and footer.php .

As it seems that the part you’re trying to modify is a copyright part, which is usually located in the footer of a page, i’d check first the footer.php template part inside your theme to see if that part of code is present there.

more info here on codex