Be aware that you will be asked at the end of your MCAT exam session after all your sections whether or not you want your MCAT scored. Technically, you will be asked if you want to void your test or have it scored.
Choose the VOID test option to cancel your exam. Not only does this mean you will not receive scores for your MCAT, it means that your MCAT exam will not be scored period.
Know that your choice to void or cancel your MCAT exam does NOT notify AMCAS or any medical schools you are applying to. It is if you never sat for the exam.
Understand that you will not be refunded any money after canceling your MCAT scores. Also know that if you register again for the MCAT, you will be required to pay the same fees again. Additionally, those fees increase over time, so you may have to pay more the second time around.
Make sure that you understand that you cannot cancel or void your MCAT scores once you chose to score your MCAT. Your scores will be reported to AMCAS and to the medical schools you are applying to. Again, there is no way to cancel your scores if you don't do it on the computer you used for the MCAT and immediately following your MCAT examination.