function onSystemEvent( event )
      if "applicationSuspend" == event.type or "applicationExit" == event.type then
            local destDir = system.DocumentsDirectory -- where the file is stored
            local results, reason = os.remove( system.pathForFile( "noticias.xml", destDir ) )
 
       if results then
           print( "file removed" )
       else
          print( "file does not exist", reason )
       end
 
 
     end
  end
 
Runtime:addEventListener( "system", onSystemEvent )