I've sent out a driver on a route, how can I get them back?

Once you've sent a driver off to work, they won't be able to come back until they have completed their route. You can only cancel a trip if you are the driver and exiting through the pause menu.

If you want to know how much time left your driver has, click the "Drivers" button on the main menu. You can click "Show" beside your driver list and it will provide you the remaining time for their trip.