Yes. Once you have finished with the GMAT exam, you will be shown your scores (VA, QA, Overall, IR) on the screen. In case you are not happy with the score, you can Cancel the score. If you do this, your score will not be reported and will also not feature on your score report.
In the event that you cancel your GMAT score at the exam venue but decide later that you need the score, you can reinstate the GMAT score within a short time window for a fee.