Certainly you can ....and I have done so successfully on many occasions as my ones are inclined to lean over a path - much to the consternation of Postman Pat etc...LOL
As it says ....
"Acers do appreciate a bit of help though when the central area becomes over-crowded. This can stop air circulating and make the trees more prone to fungal diseases. Every two or three years when the leaves have fallen, prune out any diseased or damaged wood. If the central part of the tree looks overcrowded, prune some of the stems and smaller branches, but maintain the overall shape of the tree."
I just lop off what is too low and in another area where it was getting too big - I just "shaped it" quite ruthlessly and it looked glorious next season. I would do it once the leaves are down.