I am getting below error when exporting file 

Access to the path 'D:\Excel\OrderDetails.xlsx' is denied.

I do not want to specify folder, just want to directly download on browser when exporting excel file 

below is my code  

        protected void Button1_Click(object sender, EventArgs e)
        {
            DataTable dt = GetDataTableFromExcel();
            List<DataTable> dts = dt.AsEnumerable()
                .GroupBy(row => row.Field<string>("Ref_ID"))
                .Select(g => g.CopyToDataTable()).ToList();

            string path = "D:\\Excel\\";
            if (!Directory.Exists(path))
            {
                Directory.CreateDirectory(path);
            }
            using (XLWorkbook wb = new XLWorkbook())
            {
                for (int i = 0; i < dts.Count; i++)
                {
                    if (!string.IsNullOrEmpty(dts[i].Rows[0][0].ToString()))
                    {
                        wb.Worksheets.Add(dts[i], dts[i].Rows[0][0].ToString());
                    }
                }
                wb.SaveAs(path + "OrderDetails.xlsx");
            }
            DownloadFile(path + "OrderDetails.xlsx");
        }
        public void DownloadFile(string path)
        {
            Response.Clear();
            Response.ContentType = "application/octet-stream";
            Response.AddHeader("content-disposition", "attachment;filename=" + Path.GetFileName(path));
            Response.WriteFile(path);
            Response.End();
        }