Did you list your home as a FSBO (for sale by owner) on Zillow?? If so, you'll have to go and edit your own listing. It is very doubtful that an agent acutally edited your property photos. They cannot do that unless they are the listing agent and submitted the property for sale themselves (or via the MLS).
Also...Keep in mind, that the reason why you can list your home for FREE on that site is because us agents PAY for advertising and lead generation. So yes, your listing will show several agents next to your listing. People can choose to contact them or not. But that's what you get when you try to sell your home for free.