if ftp.Login=True then
     begin
      ftp.ChangeWorkingDir(ip+'/voice');
      if FindFirst(edt1.Text+'*.wav',faAnyFile,search)=0 then
  begin
      repeat
       if search.Size > 600000 then
       begin
   ftp.DataStream.LoadFromFile(edt1.Text+search.Name);
   ftp.StoreFile(search.Name, False);
   DeleteFile(edt1.text+search.Name);
       end;
      until
        FindNext(search)<>0;
   FindClose(search);
   ftp.Logout;
   ftp.Free;

DeleteFile
....
Return Value
If the function succeeds, the return value is nonzero.

If the function fails, the return value is 0 (zero). To get extended error information, call GetLastError.