The first option controls whether you will notify the user that you have unsubscribed them. The second option controls whether all the Mailman list owners will be notified of the user removals.
The textbox works the same way as that in the Mass Subscription page. Only one address can be listed per line. You do not need to add real names even if you added them when an address was subscribed.
You can also upload a text file with a list of addresses using the browse button. This list must be in plain text format (word, lotus word, or any other special formated file will not work).
When you submit your addresses, the page will reload with a list at the top of the page displaying those addresses just subscribed. It will also display any addresses it didn't understand because of a formatting issue and inform you those addresses were not added.