Mac Informer is designed to keep you informed about latest versions of the applications installed in your Mac. Its installation does not affect your system's functionality. It is recommended to be kept. However, you can use many software to remove Mac Informer. Here's a list of them. I suggest you to use Graveyard or Ctrl Alt Delete because these are free and easy to use.
Alternatively, to delete it you can drag the icon from Applications to Recyle Bin.