/**
 * The following snippet shows you how to limit the toolbar buttons to the 
 * text format dropdown, and the bold and italic buttons. 
 *
 * @access   public
 * @param    $buttons        An array of teenyMCE buttons.
 * @param    $editor_id      Unique editor identifier, e.g. 'content'.
 * @return   array           List of teenyMCE buttons
 */
function prefix_custom_teeny_mce_buttons( $buttons, $editor_id ) {
    
    $buttons = array( 'formatselect', 'bold', 'italic' );
    return $buttons;

}
add_filter( 'teeny_mce_buttons', 'prefix_custom_teeny_mce_buttons', 10, 2 );