De-register widgets

gistfile1.phtml

function mytheme_remove_default_widgets() {
        $widgets = array(
                'WP_Nav_Menu_Widget',
                'WP_Widget_Archives',
                'WP_Widget_Calendar',
                'WP_Widget_Categories',
                'WP_Widget_Meta',
                'WP_Widget_Pages',
                'WP_Widget_Recent_Comments',
                'WP_Widget_Recent_Posts',
                'WP_Widget_RSS',
                'WP_Widget_Search',
                'WP_Widget_Tag_Cloud'
        );

        foreach ( $widgets as $widget ) {
                unregister_widget( $widget );
        }
}
add_action( 'widgets_init', 'mytheme_remove_default_widgets', 11 );