A weird question. Never met anyone who wanted a smaller Trachie. The only way I can think of is to put it in a smallish pot and sort of bonsai it. They don't take kindly to this though so have you thought of selling it and buying, say, a Chamaerops humilis?

You can't, it's one of those plants that just grows one stem and the growing point is at the top. If it's in a pot, why not find someone who would like it in exchange for buying you a smaller one?