The Unregister component is meant to be used to allow users to unregister themselves from a website.  The Mambo core provides functionality for registration but doesn't provide for unregistration.

Typically this component will be installed as a Main  Menu item (MOS Component) or used via the companion module (see below). 

The first "screen" of the component confirms that the user wants to be unregistered.  The user is required to enter their password (twice).  The component confirms that the passwords match and are the correct password.  Provided that every is correct the user is removed from the mos_users table.

It is possible that the user was the author of content.  The Unregister component changes the author of any such records to be the admin user.  The same is done for any content that was modified by the user.

The Unregister component also checks-in any content that was currently checked-out by the user.

The module

Along with the Unregister component there is a module that is a simple wrapper to the component.  Site developers who wish to provide a link to the component but don't want to put the link in the main menu (or user menu) can install and publish the Unregister module instead.