In my opinion, the moldy egg will not harm the rest of the eggs. Their shell covering protects them. However, touching from human hands, oils and wiping them can remove or dimish their eggs natural protection.

I have incubated a clutch of eggs that had one mold. The rest of the eggs hatched without incident. I did not bother any of the eggs except to let air circulate from time to time.

This is one option. Someone else may have another.