Delete Query in Linq in asp.net

MyLinqDataClassesDataContext mylinq = new MyLinqDataClassesDataContext();

var deleteuser = from p in mylinq.userCredentials

                         where p.uname_db.Contains(TextBox3.Text)

                         select p;

    mylinq.userCredentials.DeleteAllOnSubmit(deleteuser);

    mylinq.SubmitChanges();