LOL I just this minute posted a message saying I so wanted a Strelitzia here in Texas but the climate is a killer. Yes, remove the dead flowers and you can thin the leaves out if you want but it isn't really necessary. Strelitzias are often propogated from leaf cuttings, so if you want more of them, bear that in mind.

It is not possible to propagate strelitzias from leafcuttings but I think you want to say from shoots.
The plant starts deviding it self in fans and each fan is a plant but normaly still conected with the rest.
When you divide them normaly you need to root them again so you will have a separated plant.
We normaly don't cut the flowers but pull them out of the motherplant so you don't get flowerrests in the plant.
Cleaning out will give more light inside the plant and give stronger and shorter flowers.

Hi, the plants definitely do need to be "thinned" out when they become too bulky ... we had enormous success with transplanting roots and shoots from the Parent plant - definitely not leaves?! BTW they do seem to "sulk" for some years after the shifting. Much like cycads do.

Look forward to sharing news ... from the green hills of Kwazulu Natal
Susan