Hmm, tough one. I never throw out old stuff or delete my work (not after I lost about 30 pages and 6+ hours of work thanks to an unforseen computercrash). I do edit a lot, scrap phrases and re-write paragraphs, fine-tune jokes and all that stuff but I never throw it away. For me, writing is because I like doing it. I don't do it for the moeny, nor for fame, nor to please my family or friends. I do it for me, and for the joy it gives me. If people like it, all the better. If they don't, I couldn't care less (criticism on how to improve it notwithstanding. Those I will check and if I feel the criticism was indeed valid, use to improve my work).

So why do you write? What is your motivation? Do you do it for yourself and for the joy of it or for another reason? Why destroy something you've created? Why the distrust in your friends' judgment? On showing it online: there's plenty of sites where you can post it anonynously, you know that. Who's ever going to find out it was you who was the author, if you don't want people to know? And even if they do, so what? it's your work. If they criticize your poems or make fun of it, maybe this anecdote helps.

A friend of mine spent quite some time in Spain and even though he could speak the language a bit, he wasn't fluent in Spanish. Several of the locals there made fun of his (to them) obvious errors and teased him. My friend, being fed up with their criticism, one evening heard them making fun again of his mispronunciation, turned around and said in his best spanish, eerily calm: 'IF you have mastered MY language the same way as I have mastered YOUR language, you may open your mouth. If you have NOT mastered my language the way I have mastered YOUR language, you can shut your goddamn gob.' A shocked silence followed, the locals exploded with laughter and a round of drinks followed soon. Ever since, whenever someone makes fun of someone else because their efforts in whatever fall short, they look at one another and just say: 'If you speak my language...' and everyone knows exactly what they mean.

In other words, people may criticize your poems if their work is vastly better. If not...

edit: a word