Как сделать удаление строк из файла?

private static String FileName = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), "SomeFile.txt"); 
 
private static Dictionary<string, int> AllNames()
{
    return File
      .ReadLines(FileName)
      .Where(line => !string.IsNullOrWhiteSpace(line))
      .Select(item => item.Split(' '))
      .ToDictionary(items => items[0],
                    items => int.Parse(items[1]));
}
 
private static void WriteNames(Dictionary<string, int> AllNames)
{
    var lines = AllNames
       .Select(kvp => kvp.Key + " " + kvp.Value.ToString())
       .ToArray();
    File.WriteAllLines(FileName, lines);
}
 
private void button1_Click(object sender, EventArgs e)
{
    var all = AllNames();             
 
    var tops = all
      .OrderBy(pair => pair.Value)
      .ThenBy(pair => pair.Key, StringComparer.Ordinal)
      .Take(5)
      .ToArray();
 
    // ... your existing code to work with "tops" ...
 
    // remove them from the dictionary
    foreach(var top5 in tops)
    {
        all.Remove(top5.Key);
    }
 
    // write out the new file
    WriteNames(all);
}