Pruning saw - best not done till April, really, but if that tree has been moved recently in a state of 'bare root' and not transplanted from a large pot, it might be better to risk doing it now in case it suffers transition shock (likely, at that size) and dies. You can use a chain saw if you like, but it won't look pretty whichever implement you use - suggest you cut down by half, leaving no leaves currently, or reduce down to about a foot above the crook in the middle, where there's a tuft of growth. Angle the cuts to allow rain to run off. The tree, if it copes with the move, should produce new tufts of growth from where you've cut, and possibly lower down. If it recovers and grows, these trees, in a sheltered spot, can easily make 20 feet, and its not a good idea to prune regularly, though cutting nearly to the ground is an option, when it will grow again. Sometimes, a hard winter kills them, or they get damaged, get slime flux,or die back to the base - if you're lucky, they grow again from the bottom.

Thank you so much for your reply. I have just used the Fiskers extension secateurs, it really did the job well. I hope the transition does not kill it. I dug deep to get it out this morning, but ended up snapping the underground trunk. I did manage to get lots of roots, so I hope it survives. Thank you so much for your reply. Kindest regards, Paul

Great looking Cordyline: most of the plants in my neighbours gardens came from me. so good to see others doing the same. The red/black ones are less hardy than the green ones and if the forecast is for below -5C or the like, esp for a few days, then you will need to wrap the crowns and in prolonged deep cold the trunk (just use lots of horticultural fleece).

Thank you Botonic for your reply, The crowns are to high to wrap in fleece. It has survived at least a decade without fleeces, so I´ll take my chances. I will see if it survives the transition first. It´s about 14ft high at the moment. I´m not sure how big they grow?

Even wrapping the trunk in fleece will give some protection, plus a good deep mulch of bark chippings.
They grow 30+ ft in the right conditions.

Invest in a 10-step fibreglass stepladder.