The imaging hosting utility here didn't hijack all the photos on your computer, and it doesn't download software or change your desktop.
First, you have to browse to each photo individually, specify it's size, etc., and then copy the URL it generates.
Second, if you are a photographer who sells photos, you probably have hundreds of photos, many in RAW format that are 10 mb, 16 mb, etc. The program couldn't "hijack" and upload that much content even if you left it running for days.
I have several thousand photos on my computer, most in RAW format, and I have been using that utility for about three years now. The version here and the stand alone website. It has never installed software on my computer, never copied a photo I didn't tell it to, and never done more than one photo at a time.
Your issues lie elsewhere.