You can't - these are large, stately trees, so in smaller gardens, they're only ever temporary visitors, for up to about 10 years. Some people keep them and remove the lower branches, but that obviously doesn't reduce the height.

they are one of the oldest forms of life still in the form they were well before the dinosaurs , insects everything and the only place they grow from is the tip so bamboo is right . ironicly they dont grow nativley anywear near monkies which is quite puzzling lol .

It's properly a "Monkey Puzzle Tree"--it's European discoverers probably thought that the chances of a monkey climbing the spiny trunk and branches were pretty slim! Unfortunately for pruning purposes, its growth habit is the same as spruce and fir, with a central leader and whorls of branches, so it is impossible to keep the height down without ruining the shape. Creative yearly pruning could allow it to stay lower, but with the silhouette of a weathered old pine tree--quite a different statement in the garden!

elizebethens were the ones who thaught how unclimbable this tree is for what its worth when these trees became fashionable . great minds think alike lol .