Use Advanced Logging

    using GroupDocs.Redaction.Options;
    /// <summary>
    /// This is an example of ILogger implementation, tracking count of error messages.
    /// </summary>
    public class CustomLogger : ILogger
    {
        public List<string> Errors { get; private set; }
        public List<string> Traces { get; private set; }
        public List<string> Warnings { get; private set; }

        public bool HasErrors { get { return Errors.Count > 0; } }

        public CustomLogger()
        {
            Errors = new List<string>();
            Traces = new List<string>();
            Warnings = new List<string>();
        }

        public void Error(string message)
        {
            Errors.Add(message);
        }

        public void Trace(string message)
        {
            Traces.Add(message);
        }

        public void Warning(string message)
        {
            Warnings.Add(message);
        }
    }

using (Stream stream = File.Open(@"sample.docx", FileMode.Open, FileAccess.ReadWrite))
{
   var logger = new CustomLogger();
   using (Redactor redactor = new Redactor(stream, new LoadOptions(), new RedactorSettings(logger)))
   {
      // Here we can use document instance to make redactions
      redactor.Apply(new DeleteAnnotationRedaction());
      if (!logger.HasErrors)
      {   
         redactor.Save();
      }
   }
}