I'd leave the stem with growth alone but yes chop down the others. We my oh inadvertently chopped mine off at the knees it did regrow and you cant tell now. He still goes at things like a Bull in a china shop though, once he gets the chain saw fired up there is no stopping him :o)

Chain saw massacre in E. Yorks! I like a good go at pruning, good for the soul.
C. alpine is pretty robust and can stand some hacking. I have never taken one right down to the ground but as long as there are still green shoots left it should be OK.

Thanks both. I'll get snipping when the hail storms disappear!
Luckily I don't own a chainsaw ;-)