It really has nothing to do with sperm. It is actually just hemipene shed. Ball pythons do not produce sperm plugs. Unfortunately it is just one of the terms that we in the Ball world use incorrectly. It should be just fine if left alone or you could gently pull it off if you so desire.
You are the first person I ever hear to say this... So if they do not produce sperm plugs, what is it that they produce that leads all these breeders to believe the male is ready to go?