You have the option to delete a list or to delete all profiles within a list.
Delete a list
To delete a list, click on Audience > Lists. Select "Delete" from the triple-dot menu on the right. This action will delete your list but will not delete the profiles from that list from your account.
Alternatively, you can delete a list by clicking on the list, and click on the arrow menu next to the list name. From the drop-down menu, click on "Delete List" to delete the list.
Delete an Audience
To delete an existing Audience, first select the Audience you want to delete. Once in your Audience, you can click the arrow menu on the top of your screen. From the drop-down, click on Delete All Profiles to delete ALL the profiles in that given list. This action cannot be reversed and the deleted profile will not be recoverable. It can take up to 24 hours for this action remove this data.
Delete All Profiles: this will delete the profiles in your Audience from your account but will keep the Audience name and criteria.
Delete List: this action will delete ALL profiles in your Audience AND the list from your list view.