How to remove watermark for your graduation photos

I'll take gradimages.com as an example

1. Go to the page that contains your graduation photos. Mine is:
    www.gradimages.com/XXXXX
2. Pick the image you want to download for free, zoom in and find its photo ID
3. If you are using Google Chrome, press fn + F12 or F12 to turn on developer mode (other browsers should be similar)
4. After the browser codes are loaded, click on it and press cmd + F to search
5. Search that image ID, you will find an url that links to your photo!!! Mine is:
     isc01.gradimages.com/******/***.jpg?preset=p
6. remove that preset=p you will get a small image without water mark

7.Play with that URL to find out more!