Is it too late to take the dead limbs off my smoke bush?
I live in Denver, Colorado.
The short answer to your question is that dead, diseased, or damaged wood can and should be removed at any time for the continued health of your tree or shrub.
If your smoke bush has a lot of dead wood, it may be advisable to cut it back more severely. From closer to home, here is a good guide to pruning: https://dspace.library.colostate.edu/bitstream/handle/10217/44466/Pruning_Cuts.pdf?sequence=2&isAllowed=y
You may also be interested to know that Colorado has a Master Gardener program which offers courses in pruning and tree care: