Remove some (or all) default wordpress formats like Paragraph, Heading 1, Heading 2, Pre, …
/*
* Modify TinyMCE editor to remove H1, H2, H3,….
*/
add_filter('tiny_mce_before_init', 'tiny_mce_remove_unused_formats' );
function tiny_mce_remove_unused_formats($init)
{
// Remove desired format
$init['block_formats'] = 'Paragraph=p;Heading 1=H1;Heading 2=h2;Heading 3=h3;Heading 4=h4;Heading 5=h5;Heading 6=h6;Address=address;Pre=pre';
return $init;
}