remove QueryString

Question

what this code not remove Query String ?

protected void Page_Load(object sender, EventArgs e)

{

// Get the NameValueCollection

PropertyInfo isreadonly = typeof(System.Collections.Specialized.NameValueCollection).GetProperty("IsReadOnly", BindingFlags.Instance | BindingFlags.NonPublic);

// make collection editable

isreadonly.SetValue(this.Request.QueryString, false, null);

// remove

Request.QueryString.Remove("b");

}

protected void Button1_Click(object sender, EventArgs e)

{

Response.Redirect("Default.aspx?b=123");

}