Sambucus nigra and any of it's varieties such as Black Lace can be pruned as lightly or as hard as you want. This can be done now or as late as early summer if needed. They really are tough and the one I used to have just had any branches removed as and when needed, especially if they encroached too far on the path. Just remember that if you cut of all the wood back, you will just get lots of vigorous shoots and no flowers which are quite attractive on this, though not as good as the variety Black Beauty.

Just to add that if you want another one or a dozen specimens, cuttings from this shrub (hard wood or soft wood) take extremely easily, so don't waste all your prunings. I absolutely love this little tree for its pink white flowers and attractive foliage.