Deleting an app on your iPhone doesn't necessarily get rid of it altogether. Here's how you can permanently remove an app from your iPhone.
1. Select apps from the left column in iTunes.
2. Find the app you want to remove permanently.
3. Right click the app's icon and choose Delete.
4. When prompted affirm that you want to delete the app.
5. You will be prompted again to see if you want to move files to the trash. Affirm that you want to and the files will be placed in the trash.
6. Empty your trash can.
Voila! The iPhone app is gone permanently.
iPhone Tips: How to Permanently Delete an App | iPhone Tips