using static System.Console;

​

public class Program {

    public static void Main() {

        var texto = "Abcc111de12234";

        var lista = new char[texto.Length];

        for (int i = 0, j = 0; i < texto.Length; i++) if (!char.IsDigit(texto[i]) || (i == 0 || texto[i] != texto[i - 1])) lista[j++] = texto[i];

        WriteLine(new string(lista));

    }

}

​

​