At any given time you can reset your Nexus 4 smartphone to the factory default settings, meaning you will bring your phone back to the same state as it was on a day when you took it out of the box.
You just bought Nexus 4 and you don't know anything about Android operating system, so I will guide you through literally first steps on this great phone.
If for some reason your Android powered smartphone does not perform as good as it used to, or you want to sell it I suggest you to bring it to its original factory state.
If you are afraid your friends, kids or any other person you are borrowing your iPad to, might delete an app by mistake or even intentionally, you can enable restrictions on individual all of the apps.
