Simply drop-crotch as you would the top of a tree. Don't fall into the temptation of snipping here and there out of habit. In extreme northern climates, there is little choice because winter cold and drying usually cause dieback to near the soil line. Failure to remove these dead or weakened canes in spring results in an unsightly shrub later in the summer and will tend to crowd the shoots arising from the base. Crowded shoots and flowers will be weak.
Some shrubs have only a single main trunk and are really small trees.
This includes several of the Viburnum species, Euonymus and shrubby forms of Rhamnus . Obviously, do not cut these shrubs to the ground. Treat them in the same manner as a small tree. Occasional thinning of interfering, weak or excessive growth and stepping back by drop-crotch methods may be necessary. This should be done in late winter.