How to avoid File Blocking

using (var st = new FileStream(MenifestPath, FileMode.Open, FileAccess.Read))
{
    using (TextReader r = new StreamReader(st))
    {
       var xml = r.ReadToEnd();
           r.Close();
           st.Close();
          //................ Rest of our operations
    }
}

string xmlText = File.ReadAllText(ManifestFile);