From your Contacts dashboard, hover over Options for any list, then choose Clear or Delete:
You will be clearing contacts out of that list ONLY. Contacts in any other existing lists will stay there. This cannot be undone.
You have 2 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.