That gets added because your theme supports post-formats
.
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:
<?php
add_action('after_setup_theme', 'wpse65653_remove_formats', 100);
function wpse65653_remove_formats()
{
remove_theme_support('post-formats');
}
Or look for the the line in your theme's functions.php
file:
add_theme_support('post-formats');
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.