I have a very simple module which pulls together user bits and pieces so I can make a judgement if they are spammers or not   If so, I have a delete user button in the module to make life easier.  Last thing I need to finish the module is to do the delete itself.

To get rid of links to user profiles I need to do a hard delete (completely remove the user).  After much research and playing around with the API, I'm still unable to do this.  Would be great if anyone provide me with some hints. 

Thanks Ash, the links you provided sorted everything out.

For anyone else looking, the key is:

UserController userController = new UserController();
UserInfo user = userController.GetUser(portalID, userID);
UserController.DeleteUser(ref user, true, false); // soft delete of user
UserController.RemoveUser(user); // remove user to complete hard delete