Yes you can, and it wont be detrimental to the plant. I'd probably do it in stages, lifting the lower part by half the amount you think you want. leave it a month or so then recut until you get the desired effect.
[as I said to my daughter you cant sew them back on once you have cut them off. She over did it and ended up unhappy and ended up taking the top off as if she'd pruned it by half.]

That's really sound advice,thank you Eileen...I'm glad I asked the question.