public static void Main()
DataTable dt = new DataTable();
dt.Columns.Add("BRANCH", typeof(string));
dt.Columns.Add("TYPE", typeof(string));
dt.Columns.Add("ID", typeof(string));
dt.Rows.Add(new object[] { "1V", "R", "ZZ"});
dt.Rows.Add(new object[] { "1A", "R", "ZZ"});
dt.Rows.Add(new object[] { "3", "W", "V"});
dt.Rows.Add(new object[] { "2V", "R", "VW"});
dt.Rows.Add(new object[] { "1", "R", "NI"});
dt.Rows.Add(new object[] { "4", "I", "MA"});
dt.Rows.Add(new object[] { "1B", "R", "SZ"});
foreach (DataRow row in dt.Rows)
row["BRANCH"] = row["BRANCH"].ToString().Substring(0,1);
Console.WriteLine(row["BRANCH"].ToString());