Once you delete a list, any forms and subscribers on that list are deleted as well.

Think before you delete a list! This cannot be undone!

Since Deletion is considered a 'global action' in your account if you delete a list which contains an address that is also on another list then that subscriber will be deleted from both lists.  If wish to simply Remove subscribers from your list you should simply add them to your Do Not Mail list.  This can be found under Subscribers> Do Not Mail.