Widget Creation – Not updating upon removal

Hi.
I just created my first custom widget with multiple instances. The plugin is pretty straight forward – it adds posts to the sidebar from a user-defined category. I based the code off of a mix of the text widget and the “tutorial code” at the bottom of /wp-includes/widgets.php. Everything has gone smoothly so far but when I remove an instance of the widget, the data does not get deleted from the database. If any widget whizzes could take a look at the code, I would be very appreciative:)

I uploaded the full source to:
https://wordpress.codebin.ca/1012481

Thanks for reading!