You can move all the orders assigned to one driver to another simply.

• Go to Optimize Route
• From the timeline section, click on the 3-dots button near the driver’s name
• Select Move all orders to option and click on the driver name to which you wish to move the orders and preview the changes on the map
• Optionally, you can choose to reoptimize the orders for one driver by dragging one of the orders over his/her name
• Click on Save changes button to commit them