Witholing an AP Score on UCAS

I am an American applying to Oxford PPE who, through now fault of my own, has one low score on an AP exam. Long story short, my school forced me to take it when I was not ready.

I am going to get the CollegeBoard to delete the score. Then I am going to call UCAS, and try to get a statement in writing from them that since I no longer have access to the score and cannot verify that I ever took this test, so I do not have to submit it.

The alternative would be to explain my situation to Oxford, but I feel this is riskier.

Does anyone know of any bad stories of an American applying to Oxford who withheld their AP score. Of course there are bad stories about withholding a score since UCAS contacts the British exam board- but specifically for Americans for APs? UCAS does not seem to have a good relationship with the CollegeBoard.
Does anyone have any better ideas?

How does one get CollegeBoard to delete an AP exam score? Cancellations need to occur some time BEFORE scores are released, if I am not mistaken.