List<int> delUserIds = new List<int>;//自己赋值
List<user> users = udc.user.Where(u => u.id in delUserIds );
foreach(user delUser in users)
{
     udc.user.DeleteOnSubmit(user);
     udc.SubmitChanges();
}

------解决方案--------------------
http://www.cnblogs.com/jeffreyzhao/archive/2008/03/05/linq-to-sql-batch-delete-extension.html

------解决方案--------------------
DeleteAllOnSubmit

------解决方案--------------------
DeleteOnSubmit