ProviderHostedCustomUIActionsWeb.Models.ContactsListManager.DeleteAllItems C# (CSharp) Method

        public void DeleteAllItems()
        {
            CamlQuery camlQuery = new CamlQuery();
              camlQuery.ViewXml = @"<View><Query><Where><IsNotNull><FieldRef Name='ID' /></IsNotNull></Where></Query><ViewFields><FieldRef Name='ID' /></ViewFields></View>";
              ListItemCollection items = contactsList.GetItems(camlQuery);
              clientContext.Load(items);
              clientContext.ExecuteQuery();

              foreach (var item in items) {
            contactsList.GetItemById(item.Id).DeleteObject();
            clientContext.ExecuteQuery();
              }
        }

 public ActionResult DeleteAllItems(string SPListId)
 {
     ContactsListManager contactsListManager = new ContactsListManager(new Guid(SPListId));
       contactsListManager.DeleteAllItems();
       return View();
 }