It's an elderberry which does well up from zone 3- 8. Not much information on pruning practises, but I note it is described as a decidous plant. So perhaps to be on the safe side, just mulch it and observe it next spring to see where it starts to bud up from . Perhaps it will bud up from old wood or perhaps from the root core. In practise, I prefer not to prune any plants severely in the fall time because the branches and twigs act to catch the snow which in turn creates a form of insulation. I do my heavy pruning in early spring and only after I start seeing signs of growth.

I have a sutherland gold elder. As ianna has said, they are very hardy as well as very forgiving about being pruned.
If you want a low bushy shrub, then cut it low to the ground making sure that you leave a small framework of older branches for the new sprouts to appear on.
If you want a larger shrub, then only prune it down by half.
You can also prune it during the growing season to increase its branching and appearance.
I agree with ianna that pruning in the spring is best, so you can see what has been winter damaged and what is actively going to grow.

Ian

do deer like this sambucus?

I don't think so. Every shrub I've planted at one time or another has been chewed to bits by deer but never sambucus and I have quite a few. Loads of wild ones and several varietys from nurseries.

I've had one of these for a few years. The first year I planted it was fine, the second year it got WAY big and methought..uh oh...it's too big for this space..

So I whacked it back pretty hard - took about 2/3 of it off and it's been very well behaved ever since..