Disable particluar Date(s) from the Calender Control.

protected void Calendar1_DayRender(object sender, DayRenderEventArgs e)
{
          //Here whatever user pass the date into textbox then it will parse that date as DateTime…
          DateTime myDateTime = DateTime.Parse(txtUserDate.Text);
          if (e.Day.Date == myDateTime)
          {
                    //Disable Given Date....
                    e.Day.IsSelectable = false;
          }
}