That is an issue! All depends what cultural background you bear. In Japan you would say "It's difficult, I am not worth it." and this is considered to be enough while in NY ... well, most of it is just fine. I suggest honesty, no figurative speaking and no emotions. "I am not interested" will do much better than poems that one can interpret in many ways, maybe you are just playing? Being aggressive or offensive may be perceived as an challenge and give opposite results. Don't cut the cord, unplug it first. And avoid "please" - victims are easy targets. "Would you mind stop spamming me?", "I refuse to answer this question","I tried to convince myself but no" - clear and painless, even if bitter. Want to be sophisticated. Be! Can't? aaa such a shame ;)

You could say you need to stay home or go home to wax the cat. If you are going to be working or communicating with a man for an extended period, but do not want any romantic interest from him, I am amazed that so few women take the straightforward approach and tell him outright that you do not want any romantic interests coming into play.

For what situation? A polite and sophisticated rejection for a potential suitor would be quite different to that for a potential employee!