Abutilons are one of the few shrubs that can be pruned at any time during their active growing season. They quickly start re-growth and subsequent flowering.
Simply prune as and when required. In particular, after the winter damage, when most types can be cut back quite hard. This will encourage strong growth - which will soon regain its original height.
If grown as a patio pot plant, and taken into protective care for the winter, the Abutilon can be pruned to shape either as a shrub or a single stem 'feathered' specimen.
For a single stem mini-tree, either prune off the laterals - AFTER regrowth has started in spring, or prune back all laterals to within 6in of the main central stem or trunk. This will encourage growths which can then be attractively trimmed into a narrow pyramid - especially effective for the variegated foliage types.
The same single-stem treatment can be applied when Abutilons are grown as houseplant or conservatory speciments.
Wall grown Abutilons such as Abutilon megapotamicum should be pruned in early spring. This is best done by pruning wayward branches back to a main framework.
Larger shrub type Abutilons such as the semi evergreen Abutilon suntense should be pruned in the main to tidy the winter damaged branches which are apt to break under the weight of snow - or in heavy winds (Not the best situation for growing them)