Does rubbing alcohol kill dry precum?

Pre-Cum. Pre-cum is semen. It houses fresh sperm. Are you asking if rubbing alcohol can or should kill sperm? If one has precum on their penis one can wash this with soap and water. I would not recommend putting rubbing alcohol on the penis skin. If you meant something else please ask again.
Kill what? Precum is not 'alive' so it can't be killed. I assume you're asking about killing infectious pathogens in precum. It's unlikely that you could pick up anything from precum that has already dried, but if you're feeling a little obsessive about this, alcohol will kill just about anything you'd worry about.