To uninstall an iPhone application, go to the Home screen of the iPhone, tap and hold the application you want to uninstall, click the “X” icon next to it, and then click Delete. The uninstalled application remains in your iTunes library until you delete it from iTunes.
To delete the application permanently from your iTunes library, go to iTunes on your computer, click the Library option at the top-left corner of the iTunes home page, and then click Apps. If you cannot find the Apps option, go to Edit, and select Apps under Sources. Click on the application you want to delete, and then click Delete App on the pop-up window. On the new window, click Move to Recycle Bin to permanently remove the selected application from the library.
Alternatively, if you want to uninstall an application from the Settings menu of your iPhone, tap Settings on the Home screen, and tap Usage on the General tab. Tap on the application you want to delete, or click Show All Apps if the application does not appear on the provided list. Click Delete App after tapping on the application you want to delete, and then click Delete App again on the confirmation window to delete the selected application.