How to Change the Route in iPhone Maps
The iPhone "Maps" application, which comes as a standard feature on all iPhones, is capable of showing you the area surrounding one location or routing you between two points. A route entered into the application stays until it is manually deleted, so each time you open the app the previous route will still display. Entering a new route into the application takes just a few seconds, but you must have a current connection to 3G or Wi-Fi for the directions to be generated.
Open the mapping application on your iPhone by tapping the "Maps" icon on your home screen once.
Tap the "Directions" icon at the bottom of the "Maps" application.
Choose the "Edit" button in the top-left corner of the screen.
Tap inside the "Start" field, which says "Current Location" by default, and enter a new starting address for your route using the keyboard that appears. Change the end point for your route by tapping inside the "End" field and typing an address.
Reverse the start and end points by tapping the curly arrow immediately to the left of the "Start" and "End" fields.
Tap the "Route" button in the top right corner of the screen to execute the new route.