WP-Mix

Delivering a clean custom theme involves removing components or features that will not be used. Here’s how to disable WordPress default widgets:

Disable all default widgets

Just add the following to your theme’s functions.php file:

// disable default widgets
function diw_disable_default_widgets() {
	if(function_exists('unregister_sidebar_widget')) {
		unregister_widget('WP_Widget_Archives');
		unregister_widget('WP_Widget_Calendar');
		unregister_widget('WP_Widget_Categories');
		unregister_widget('WP_Widget_Links');
		unregister_widget('WP_Widget_Meta');
		unregister_widget('WP_Widget_Pages');
		unregister_widget('WP_Widget_Recent_Comments');
		unregister_widget('WP_Widget_Recent_Posts');
		unregister_widget('WP_Widget_RSS');
		unregister_widget('WP_Widget_Search');
		unregister_widget('WP_Widget_Tag_Cloud');
		unregister_widget('WP_Widget_Text');
	}
}
add_action('widgets_init', 'diw_disable_default_widgets');

Remember to test and fine-tune as needed!

Disable all default widgets for a specific user

function remove_menus() {
	global $menu;
	global $current_user;
	get_currentuserinfo();
	if($current_user->user_login == 'username') {
		$restricted = array(__('Posts'),
			__('Media'),
			__('Links'),
			__('Pages'),
			__('Comments'),
			__('Appearance'),
			__('Plugins'),
			__('Users'),
			__('Tools'),
			__('Settings')
		);
		end ($menu);
		while (prev($menu)){
			$value = explode(' ',$menu[key($menu)][0]);
			if(in_array($value[0] != NULL?$value[0]:"" , $restricted)){ unset($menu[key($menu)]); }
		}
	}
}
add_action('admin_menu', 'remove_menus');