using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        // using System.Linq; importar esta libreria para usar el metodo de extension Where(predicate) linea 19

​

        string myString = "asd<RS>asd";

        string trimmedString = string.Empty;

        string stringToCompare = "<RS>";        

        int startPosition = 0;

        startPosition = myString.IndexOf(stringToCompare);

        char[] charString = myString.ToCharArray();

        int numIndex = startPosition + stringToCompare.Length;

        charString = charString.Where((val, idx) => idx != numIndex).ToArray();

        trimmedString = string.Join("", charString);

        Console.WriteLine(trimmedString);

    }

}