Save and export a txt to a network drive

I managed to save it in a specific folder, but at the same time it is staying in the download folder and I do not know how to remove it so that it is only saved in the path I am passing through

using (SqlCommand cmd = new SqlCommand( "select * from prueba ") 
using (SqlDataAdapter sda = new SqlDataAdapter())
{
    cmd.Connection = con;
    sda.SelectCommand = cmd;
    using (DataTable dt = new DataTable())
    {
        sda.Fill(dt);

        string txt = string.Empty;

        foreach (DataRow row in dt.Rows)
        {
            foreach (DataColumn column in dt.Columns)
            {
                //Add the Data rows.

                if (column.ColumnName.Equals("cantidadF"))
                {
                    txt += row[column.ColumnName].ToString().Replace(",000", "").Replace(".000", "");

                }
                else if (column.ColumnName.Equals("cantidade"))
                {
                    txt += row[column.ColumnName].ToString().Replace(",000", "").Replace(".000", "");
                }
                else if (column.ColumnName.Equals("Peso"))
                {
                    txt += row[column.ColumnName].ToString().Replace(",000000", "").Replace(".000000", "");
                }
                else if (column.ColumnName.Equals("Volumen"))
                {
                    txt += row[column.ColumnName].ToString().Replace(".", "").Replace(",", "").Remove(4, 3);
                    //.Remove(4,3)
                }
                else
                {
                    txt += row[column.ColumnName].ToString();
                }
            }
            //Add new line.
            txt += "\r";
        }
        //Download the Text file.
        Response.Clear();
                    Response.Buffer = true;
                    Response.AddHeader("content-disposition", "attachment;filename=" + "'" + TxtExportFactura.Text + ".txt" + "'" );
                    string filename = TxtExportFactura.Text + ".txt";
                    Response.Charset = "";
                    Response.ContentType = "application/text";
                    System.IO.File.AppendAllText(@"\xxserver\mult\mult\CROSS\" + filename, txt);
                    Response.Flush();
                    Response.End();

//...