Thanks Andre, you're right and I only saw RAR files deleted when extraction was successful.
But I remember a case when, after extraction, the resulting file was not correctly named (it had kept the name of the starting folder) and, in this case, extract with MacPAR Deluxe instead could be useful.
But it was an exception.
Perhaps it would be a little better if it was possible for the user to take the files from the trash if needed.
Usenapp is a very nice app.