Should I keep or cancel AP scores?

I decided to take the AP Euro exam without having the class or a tutor. I bought to Barron's book and read that along with buying flashcards and going through them. I took the exam and felt it was kind of rough, being pessimist I am I think I got a 2 or 3. Now I only have a few more days to cancel the scores or else I'll receive them in July at some time. My parents think that it's best for me to not cancel them and either just not report the scores or report it and believe that it will look good that I attempted an AP without having taken the class. The colleges I want to perhaps apply to are Northwestern, Johns Hopkins, and Brown University