I have some HH and its reached 5 foot tall which is OK as its for a wind break.
? Do I "prune " it like rasperberries or just leave it to carry on
5 foot is tall enough
It won't keep getting taller and taller.
Once the bushes are as thick/wide as you want them, take out some of the oldest canes at the base to encourage it to throw up new shoots. Otherwise you can usually leave it pretty much alone.