App Slammer is a great application that blocks unwanted users from using apps on your Android phone. Once the app is installed you can set the password of your choice. After that the list of all installed apps will be generated. You just have to select the app from the list.
The application will be locked after you click on its name. You can even search for the app using the option. The list can be sorted by name, date or size. See the screenshots below.