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.
You have 2 options:
1. Delete List, Keep Contacts: Deletes the list name without deleting your contacts. If a contact is on another list, we won’t delete it from the other list.
2. Delete List & Contacts: Deletes both the list and the contacts within it. This cannot be undone!