That gets added because your theme supports
You can either use a plugin (or a child theme's
functions.php) file to hook into
after_setup_theme late and remove theme support:
add_action('after_setup_theme', 'wpse65653_remove_formats', 100);
Or look for the the line in your theme's
and remove it.
The first option is a better bet. Stick it in a plugin and it will be there for the next theme you use as well.