Apple's iPhone comes with an application pre-installed called Maps. This application turns your iPhone into a GPS and allows you to get turn-by-turn directions to any destination. The iPhone uses cell towers to triangulate your current position, at which point it uses Google Maps to get you directions. If you've got predefined map points that you can't seem to remove from the application, get rid of them with just a few button taps.
Turn on your iPhone.
Tap on the Maps application.
Locate a map point that you want to remove. These map points will be marked by pins on the application's map.
Tap the blue arrow next to the dialogue box above the pin.
Select "Remove Pin."