internal static void RemoveAllSourceFiles()
        {
            foreach (byte key in taggings.Keys)
            {
                taggings.Remove(key);
            }
        }

taggings.Clear();

internal static void RemoveAllSourceFiles()
        {
           taggings.Clear();
        }

var deletionList = (from tag in taggings where <where clause> select tag.Key).ToArray();
foreach(var key in deletionList)
{
   taggings.Remove(key);
}

while Dict.Count()
  clDictObject oBj = Dict.Keys.ElementAt(dict.Count -1);
  Dict.Remove(oBj)
end while