You can't trim it back by a lot - our gardeners here trim ours regularly and have done since they were about 5 feet tall, running the hedgetrimmer over them a couple of times a year to maintain the cone shape and keep the size under control to an extent, though increased height will still occur. So you can certainly clip it over, but if you were thinking of reducing the height and width by a couple of feet or something, that's not a good idea.

I have a tree of this type, but of course don't know if it's the same as the label is long gone! Bought as a tiny plant in a pot, beautiful golden yellow with a distinct lemon scent. Of course planted too close to the drive as it was tiny, so by the time it reached over six foot it had to be trimmed. Drastic action taken this year as it has reached well over 8 feet. I cut the leader out lower than the surrounding branches that I was going to leave, as these will grow upwards and hide the centre trunk. Now slightly less that 5 foot and seems to be OK, but... I don't really care whether it recovers, it was a case of kill or cure.