Click Audience > Lists > View Lists from the left-hand navigation. Hover over Options for any list, and choose Clear or Delete.
If you pick Clear
You will be clearing contacts out of that list ONLY. Contacts in any other existing lists will stay there. This cannot be undone.
If you pick Delete
You have two options:
1. Delete List, Keep Contacts: Deletes the list name only without deleting your contacts. If a contact is on another list, we won’t delete it from the other list(s).
2. Delete List & Contacts: Deletes both the list and the contacts within it. The action itself cannot be undone, but you can re-add deleted contacts by reimporting them into the system.