Cordyline Australis. Just pull the lower, dying leaves in a downward direction and they will come away leaving a bare lower stem. As it grows taller, repeat the action and you will create light beneath.

You can saw down a trunk or two to the base, but that will likely induce new growth from the base instead...

Agree take the lower leaves off, you can if you wish cut them off near to trunk by doing so you get the architectural look similar to a pineapple, the trunks you can cut into and they normally send shoots out however sometimes they can be stubborn and refuse to shoot I have done this on many occasions with good success, if you wish to reduce it why not do one of those trunks half down then see how it responds and do the rest next year.

i'd probably take the top off one of the stems now [almost to the ground] and when you see new growth at the base remove another one. or be brutal, cut them all off and if it doesn't survive plant with something that will behave the way you want it too. its personal choice but I took mine out for the same reason.