The Asus Zenfone 2 is now running on the Android 6.0 Marshmallow software updates and as such you need to follow a new guide to root it. Once done, you get the same upsides over the Android operating system as you had before. Most of the same applications from the Google Play Store work for you again including Titanium Backup, ROM Manager, and Greenify. Plus you get to have complete control over the kernel so you can change the frequency of the CPU for underclocking and overclocking purposes.
Let’s be clear: rooting the Android operating system is not a requirement to enjoy Android. Nonetheless, if you are the type of person who likes to have full system level access, so you are then able to install anything you want, then there is never a day too early to root the device. All you need to do is be prepared to give up your warranty as rooting Android usually voids the warranty for most smartphone manufacturers and phone carrier networks. The full system level access allows you can uninstall things just as much as it lets you install them and that is the main reason why phone carrier networks and even manufacturers aren’t wanting people to root Android. It results in a percentage of people deleting the apps that they do not want running on the device to help free up memory space and thus taking away the ability for those companies to create revenue from the apps.
- The Asus Zenfone 2 is locked when you upgrade to Android 6.0 Marshmallow. However, you can downgrade back to Lollipop, and it is unlocked. Anyone who does receive an over the air update later must flash back to the stock Android 6.0 boot image before installing official Android 6.0 Marshmallow updates after they have rooted with this guide.
- Make sure that the Asus Zenfone 2 is unlocked before upgrading to Android 6.0 Marshmallow. If you upgrade to Android 6.0 Marshmallow from a locked version of Lollipop, you have to downgrade to unlock it, and then upgrade to 6.0 Marshmallow.
- You need to install a custom recovery on the Asus Zenfone 2 smartphone  before you can follow this guide to flash the SuperSU by Chainfire and end up as the root user of the device.
BEFORE WE BEGIN
- It’s a good idea to backup the Zenfone Smartphone before you decide to root it just in case you need to apply a factory reset because the rooting didn’t go to plan. You can use the custom recovery partition after your boot it up during the guide and proceed to take the NANDroid Backup if you prefer. Alternatively, head over to the Google Play Store and install the Helium application–the best app for backing up made by Koushik Dutta if you don’t yet have root access–to backup the data that is on your device.
HOW TO ROOT ASUS ZENFONE 2 RUNNING ON ANDROID 6.0 MARSHMALLOW SOFTWARE UPDATES
- Download the SuperSU package  to the computer. (The link is at the bottom of the original post).
- Connect the Asus Zenfone 2 to the computer with the USB cable.
- Open the downloads folder on the computer if you are using Window and then copy the SuperSU zip file to the internal storage SD card.
- Unplug the Asus Zenfone 2 smartphone from the computer once you know you have the SuperSU on the SD card.
- Boot the Asus Zenfone 2 smartphone into the recovery mode and the custom recovery should boot up in the display since you already swapped over the stock recovery partition for a custom version.
- Tap on the Install options from the recovery menu and then browse through to the SD card and upload the SuperSU zip file.
- Choose the option to reboot the system after you have installed the SuperSU file.
In conclusion, that is how to root Asus Zenfone 2 smartphones when they are running on the Android 6.0 Marshmallow software updates by using Chainfire’s SuperSU package. Anyone who needs to downgrade to Lollipop first can find out how that is done from this XDA-Developers forum page .
All the commands you need are available from the XDA-Developers page in the first post and the files you need for the commands are available from the Asus Zen talk forum .