.NET 4.x Удалить строки из текстовых файлов - C#

            foreach (var results in
            from first in File.ReadLines(@"C:\Users\LowFrequencySound\Desktop\1.txt")
            from second in File.ReadLines(@"C:\Users\LowFrequencySound\Desktop\2.txt")
            from third in File.ReadLines(@"C:\Users\LowFrequencySound\Desktop\3.txt")
            from fourth in File.ReadLines(@"C:\Users\LowFrequencySound\Desktop\4.txt")
            from fifth in File.ReadLines(@"C:\Users\LowFrequencySound\Desktop\5.txt")
            from sixth in File.ReadLines(@"C:\Users\LowFrequencySound\Desktop\6.txt")
            from seventh in File.ReadLines(@"C:\Users\LowFrequencySound\Desktop\7.txt")
            from eighth in File.ReadLines(@"C:\Users\LowFrequencySound\Desktop\8.txt")
            select .Concat(first, second, third, fourth, fifth, sixth, seventh, eighth))
                    string s1 = results;
                    Console.WriteLine(s111);
                    Thread.Sleep(100);
        }
        static IEnumerable<IEnumerable<T>> Cartesian<T>(IEnumerable<IEnumerable<T>> sequences)
        {
            var firstSeq = sequences.FirstOrDefault();
            if (firstSeq == null)
            {
                yield return Enumerable.Empty<T>();
                yield break;
            }
            foreach (var val in firstSeq)
            {
                foreach (var subseq in Cartesian(sequences.Skip(1)))
                    yield return new[] { val }.Concat(subseq);
            }
        }