If you own an Android phone or tab, you can easily check if it has been rooted or not. All you just need to do is to download a root checker app to the device, install, launch it and tap the “check root” button.
My favorite is the Root checker app by MobileDev.
The app simply checks if your phone has root access. You can also see information about: device and Android version, Superuser, BusyBox and Environment variables. It will check and verify the Su binary located on your device. Checks User and Group Id. The test confirms proper permissions and flags on the Su binary.