How to Change Authorization for iPhone Applications
With the iPhone App Store, users can access, purchase and download third party apps at will. Change the authorization for iPhone applications to prevent other users from installing or accessing third party apps on your device. Modify the iPhone's authorization settings so it denies access to those without the proper passcode. You may enable and disable restrictions at anytime.
Tap the "Settings" icon to open the menu.
Open the "General" tab, then tap the "Restrictions" option.
Select "Enable Restrictions." The Restrictions Passcode prompt will appear.
Enter a four digit passcode. Then confirm the passcode the in the confirmation prompt.
Slide the "Installing Apps" switch from "On" to "Off."
Select "Apps" from the Allowed Content section. A new page will load.
Select "Don't Allow Apps."
Press the "Home" button to return to the home screen.