This Droplet sits on your Desktop or Dock and when you drag a file/s over it it prompts you to allow it to permanently shred the file immediately.
I've attached an image of the process.
A droplet is basically an AppleScript that has it's own icon and is activated when you drag things onto it.
If you look at Post #4 above ^^ and click on the link there, you should see a link to a .zip file of the droplet that you can download. When the download completes, click on the .zip folder and the droplet is launched. It's now ready for use and you can store it wherever suits you.