How to disable tinyMCE button added by a plugin?

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');