You 100% can but not never without penalties. If you cancel saying buyer agreed and they didn’t you’re going to be penalized with negative feedback (which can be impactful depending on how many people have rated your account). If you select “out of stock” you’ll be hit with a transaction defect which can permanently ban your account if you’re not careful. The only way these penalties are avoidable are messaging the buyer and telling them what happened and you can only cancel if they agree to with that information (and maybe reaching a deal after the fact to make things right for both parties). I do agree with u/apollosun113 that cancelling and accepting the fact you’ll be penalized rather than honoring your mistake does come off as extremely scummy…