Thanks for your question! If your contacts have unsubscribed, they are moved into the Unsubscribed list on the left when you're in the Contacts.
You can click on Unsubscribe
Then check all the contacts and then Export
Then you can remove them from your own CSV file.
Please note that if a contact has unsubscribed, we would not add them back to your account even if they are still on a file that you import.
Hope that helps!