Root is the account that most Linux distributions offer to the first person to set up the Linux operating system from a desktop computer. It is often compared to the admin account when setting up a Windows computer or even a Mac because they typically offer the same permissions—which is complete control over the operating system and choosing what can be installed and uninstalled. Those types of permissions are necessary to run any commands that one wants to run and get access to all files. To geeks, these levels of permissions are required for obvious reasons, but the Android operating systems don’t offer a default way to get in control of the root user account that is desired for most of the same reasons that people want to get access to the root user account from the Linux distributions on desktops.
The good news is that there usually is a way to get in control of the root user account—even if Android doesn’t offer it. Third-party developers are often the ones to thank and one in particular named Chainfire who develops the SuperSU files that work for versions of Android and just about any devices that have the chance to have a custom recovery image installed that supports it.
- You need to flash the custom recovery image found in this guide on the Google Nexus 6 smartphone; we do not advise flashing it on any other device because it probably will not work.
- You need to have a computer that is running on a version of the Windows operating system to use this guide because all other operating systems cannot set up[ the version of the ADB that we have available in this guide.
BEFORE WE BEGIN
- Make sure that you unlock the Developer Options menu and enable the USB Debugging Mode on the Google Nexus 6 software before getting started with the guide so that the Android software lets you make changes to it or else the rooting and flashing of the custom recovery image cannot work.
HOW TO ROOT GOOGLE NEXUS 6 RUNNING ON THE ANDROID 7.0 NOUGAT SOFTWARE UPDATES WITH SUPERSU
- Download the TWRP Recovery  and extract it in the Downloads folder on the computer.
- Set up the ADB for Windows  on the computer and then come back and continue with this guide when that one is complete.
- Install the ADB Driver  on the computer so that the ADB commands you run can do so without any trouble.
- Download the SuperSU  but do not extract it.
- Connect the Google Nexus 6 smartphone to the computer with the USB cable that is used for charging the battery of the device.
- Open the Downloads folder to find the SuperSU and copy it over to the internal storage SD card folder for the Google Nexus 6 smartphone.
- Copy all of the TWRP files from the Downloads folder so the same folder as the ADB, so you have everything available from the same directory.
- Hold the Shift key available on the keyboard and right-click the mouse where it is white in the background of the ADB folder and choose to open a new command window here from the menu.
- Type the command “adb reboot bootloader” to get the Google Nexus 6 smartphone into the Bootloader Mode that is a required before flashing the custom recovery image on the smartphone.
- Type the command “fastboot flash recovery twrp-3.0.2-0-shamu.img” to have the custom recovery image flashed onto the Google Nexus 6 smartphone.
- Type the command “adb reboot” to get back into normal mode and as soon as you can see the smartphone reboot you need to hold down the hardware key combination to boot directly into the Recovery Mode  now and the custom recovery boots up.
- Tap on the Install button and then follow the guidelines to install the SuperSU from the SD card.
- Choose the reboot option followed by the System option to reboot the system back into the normal mode and continue using the device as you typically would but this time you now have the root access and the custom recovery image installed.
In conclusion, that is how to root Google Nexus 6 smartphones running on the Android 7.0 Nougat software updates by flashing the SuperSU from the custom recovery image. By first-time booting into the custom recovery at the end of the guide, you are taking away the possibility of the stock recovery wiping over your work. You are free to begin installing any of the root applications that you wanted to try or even get a custom ROM flashed from the custom recovery. There are root apps out there that can help you install ROMs too now since you have access to the root user account; apps like ROM Manager are always helpful to those who don’t feel confident flashing a custom ROM from the custom recovery image.