wp_unregister_sidebar_widget
Action Hook: Fires just before a widget is removed from a sidebar.
Source: wp-includes/widgets.php:494
register_widget()
Function: Register a widget
Source: wp-includes/widgets.php:112
unregister_widget()
Function: Unregisters a widget.
Source: wp-includes/widgets.php:134
register_sidebars()
Function: Creates multiple sidebars.
Source: wp-includes/widgets.php:166