RemoveAddressBookItems

// Grab all the address book items from the specified account
DocuSignWeb.AddressBookItem[] items = _apiClient.GetAddressBookItems(_accountId);
if(items.Length >= 1)
{
    // Use the address book ID of an item to remove it
    DocuSignWeb.AddressBookRemoveItem toRemove = new DocuSignWeb.AddressBookRemoveItem();
    toRemove.AddressBookID = items[0].AddressBookID;
    // Construct an array with all the items you want to remove
    DocuSignWeb.AddressBookRemoveItem[] remove = { toRemove };
    DocuSignWeb.UpdateAddressBookResult result = _apiClient.RemoveAddressBookItems(remove,
        false);
    // Confirm that the removal succeeded
    Console.WriteLine("Removed item {0} succeeded? {1}", toRemove.AddressBookID,
        result.Success);
}