I was looking to do the same thing myself. Found that removing the following code from content.php
works as well.
<div class="comments-link">
<?php comments_popup_link( '<span class="leave-reply">' . __( 'Leave a reply', 'twentytwelve' ) . '</span>', __( '1 Reply', 'twentytwelve' ), __( '% Replies', 'twentytwelve' ) ); ?>
</div><!-- .comments-link -->