In the main screen, hover over the list you want to delete and click, and click thethat appears in the bottom of the box. You can also delete a list while in the list by clicking menu on the top right, and selecting 'Delete List' . Note that deleting a list will also delete the tasks associated with the list. If you delete a shared list, the other members will receive a notification in their Notification Center. Each member's account will then have the list with the information at the time it was deleted, but it will no longer be shared.