sharepoint delete file

using (SPSite site = new SPSite(""))
            {
                using (SPWeb web = site.RootWeb)
                {
                    SPList list = web.Lists[""];
                    SPFolder folder = list.RootFolder.SubFolders[""];
                    SPFile file = folder.Files[0];
                    file.Delete();
                    file.Update();
                }
            }

 spsite["操作站点"]
web.Lists["操作列表"];