I have a dracaena that is extremely tall (36 and 48 inches in height below leafy section). Can I cut it shorter without killing it?
Yes, you can safely cut off the top. New shoots will come within months. Pruning is very good for keeping a nice shape, especially when they become too thin and long. You can also try to put the cut off top in the ground, it will root and you'll have two plants! Keep the soil for both methods not too damp, without leaves or roots they won't need so much water.
If it is D. massangeana ,sometimes called corn plant, whack away. It will grow from about 4 " lengths of trunk. That does slow it down .If you can cut a section with leaves ,it will come back faster. The plant I have now is about the twentieth cutting starting with a 4 " length of stem I got about 55 years ago . It has many siblings. Just noticed it has a two foot flower stalk , it is outside so I did not smell the stink. I also have two other draceneas, marginata , and one similar to massangeana. Both branch freely so it is very easy to cut off the leader when it is too tall and root it ,or not. Not as daunting as cutting off the only stem of a massangeana.