Oregon State University has not published any documents on how to prune a Cotinus specifically but I found this guide that shows you the two ways to prune your smoke tree (shrub).

Find out how to prune fruit trees properly, plus tips for timing your pruning right.

Question: Some of my trees need to be pruned. Can I do some of the pruning myself or should I just hire an arborist?

Do yourself and your shrubs some good by getting outside to prune them in midwinter. “This time of year, when shrubs and small trees are dormant, is an easy time to prune them,” said Sh… ...

Which shrubs to prune, mistakes to avoid— here is a guide to pruning shrubs and trees in this prime winter season.

Why you should plan to prune in February and early March Late winter to early spring when trees are still dormant (before leaves appear) is the best time to prune most trees, including fruit trees.

Find out how to prune fruit trees properly, plus tips for timing your pruning right.