I’ve found that you can manual set availability button by this attribute theme_advanced_buttons1
(for button in row 1)
Example :
function disable_mce_buttons( $opt ) {
//set button that will be show in row 1
$opt['theme_advanced_buttons1'] = 'bold,italic,strikethrough,|,bullist,numlist,blockquote,|,justifyleft,justifycenter,justifyright,|,link,unlink,wp_more,|,spellchecker,wp_fullscreen,wp_adv,separator';
return $opt;
}
add_filter('tiny_mce_before_init', 'disable_mce_buttons');