@Barrie. Please take a moment and update your public profile so that we know your location.
As Tiffany pointed out, you can easily manage the size of the plumeria by judicious branch pruning. If you would like more plumeria plants, perhaps potted, you can then root those cuttings. Rooted plumeria make great gifts to those who garden and would like to try their hand growing these exotic tropical plants.
I would love to see a picture showing the full plant and a close-up of the base of the tree. What is the diameter of that base? Do you know the variety of plumeria you have?