How to Delete an App from Your iPhone
If you no longer want the apps you have, you can delete it right from your iPhone. This is useful if you want to reduce clutter on your iPhone, or to increase available space.
Press and hold on any icon until all the icons begin to wiggle.
Tap the little x in the upper-left corner of the app you want to delete.
A dialog box appears, informing you that deleting this app will also delete all its data.
Tap the Delete button.
Keep in mind that if you’ve synced your iPhone since you downloaded the app and transferred it to your iTunes library, deleting it from your iPhone won’t get rid of it permanently. The next time you sync, it will return to your iPhone like a bad penny. To get rid of it for good, you have to remove it from your iTunes library.