Yes you can just stop if you want to. Just two pills means nothing has happened yet anyway. Do know that Prozac stays in the system about a month, unlike the other ssris which leave the body in hours. But that's actually a good thing as far as quitting usually, as the brain gets more time to adapt to being without the drug, just in case you ever reconsider.
Why have you decided to stop the medication? Do you feel you can cope without it? I would suggest that as you have only taken two you should be okay stopping them. You may get a few strange feelings, but nothing you cannot manage.
Hope you feel better soon.