using System;

using System.Text;

public class Program

{

    public static void Main()

    {

        var codigoBarras = "015424 45454 15445";

        var builder = new StringBuilder();

        foreach (var c in codigoBarras) {

            if (char.IsWhiteSpace(c))

                continue;

            builder.Append(c);

        }

        codigoBarras = builder.ToString();

    }

}