It depends.

My morality is my urge to care for other people, plus a systematization of exactly how to do that. You could easily disprove the systematization by telling me something like that giving charity to the poor increases their dependence on handouts and only leaves them worse off. I'd happily accept that correction.

I don't think you could disprove the urge to care for other people, because urges don't have truth-values.

The best you could do would be, as someone mentioned above, to prove that everyone else was an NPC without qualia. Prove that, and I'd probably just behave selfishly, except when it was too psychologically troubling to do so.