Each e-mail that you send to your site's mailing list has a link the recipient can use to unsubscribe from your mailing list, but there is also a was for you to manually remove subscribers to the list.
To delete e-mail address from the Mailing List:
Click Subscribers under Mailing List in the administration menu.
The following page will display the list of subscribers.
Check the box in the delete column next to each e-mail address you wish to remove.
Click the Delete button at the top or bottom of the list.
A confirmation page will appear. At this time you may uncheck any addresses you do not wish to remove from the list. To finally remove the addresses from the list:
Click the Delete button at the top or bottom of the list.A confirmation page will appear with a link back the list of subscribers.