How to replace caharacters in json string

[{"Skey":"5689245","Name":"test19MAY90","PhoneNo":"458652864","Email":"test@gmail.com","ProfilePic":"","Address":"VASHI","City":"mum","State":"Maharashtra","UserArea":null,"AreaId":null,"Landmark":"near station","Latitude":0.000000000,"Longitude":0.000000000,"Addressid":23}]

{"Skey":"5689245","Name":"test19MAY90","PhoneNo":"458652864","Email":"test@gmail.com","ProfilePic":"","Address":"VASHI","City":"mum","State":"Maharashtra","UserArea":null,"AreaId":null,"Landmark":"near station","Latitude":0.000000000,"Longitude":0.000000000,"Addressid":23}

if (ds.Tables[0] != null && ds.Tables[0].Rows.Count > 0)
                        {
                            DataTable dt = ds.Tables[0];
                            //jSonString = ConvertDataTableTojSonString(dt);
                            //jSonString.Replace("[", "");
                            List<dictionary><string,>> tableRows = new List<dictionary><string,>>();

                            Dictionary<string,> row;

                            foreach (DataRow dr in dt.Rows)
                            {
                                row = new Dictionary<string,>();
                                foreach (DataColumn col in dt.Columns)
                                {
                                    row.Add(col.ColumnName, dr[col]);
                                }
                                tableRows.Add(row);
                            }
                             str = serializer.Serialize(tableRows);                             
                            //str = str.Replace("[", string.Empty);
                             str = Regex.Replace(str, "[[]]", " ");
                            //return serializer.Serialize(str);