Rooting the Sony Xperia C4 smartphone running on the current Android 5.1 Lollipop update will cap off your customizing perfectly so there are no limits as to what you can do with your handset. The combination of TWRP Recovery and your root access will mean plenty of ROMs and kernels coming your way over the course of the next few years and as the device begins to age.
Anyone who wanted to install the custom recovery alone and cannot decide whether to go ahead and root the device might be interested in learning about the NANDroid Manager application — an app that is available for rooted users and works perfectly with your NANDroid backups from the custom recovery.
- You must have the bootloader unlocked on your Sony Xperia C4  before you can install a custom recovery and root the device.
- You must install a custom recovery on the Sony Xperia C4  smartphone before you can root it with the SuperSU package.
BEFORE WE BEGIN
- Enable the USB Debugging Mode from the Settings by tapping on the Menu > Settings > Developer Options > USB Debugging Mode.
- You can unlock the Developer Options if you need by tapping on the Menu > Settings > About Device > Model Number 7 times and it will say you are using the Xperia C4 device as a developer.
HOW TO ROOT SONY XPERIA C4 RUNNING ANDROID 5.1 LOLLIPOP
- Download the SuperSU package  from here directly to the desktop of your computer.
- Connect the Sony Xperia C4 smartphone to the computer with the USB cable.
- Copy the SuperSU file over to the internal storage SD card and then unplug the smartphone from the computer.
- Boot the Sony Xperia C4 to recovery mode and the TWRP you installed earlier will boot.
- Tap on the Backup option and continue to take the NANDroid backup option to backup your data just in case you need to restore them later.
- Tap on the ‘Install’ option and follow the on-screen instcruions to browse the SD card and install the SuperSU package. (Installing the SuperSU will only work if the file is still zipped. You should have transferred the file zipped over to the internal storage. Those of you struggling to get the SuperSU installed should check it is zipped.
- Go back to the main recovery menu and choose the option for rebooting the system.
The Sony Xperia C4 is now rooted and ready to start installing your rooted apps from the Google Play Store and other third-party sources online. Those of you planning on using your custom recovery to take advantage of the NANDroid Backup feature might be interested in checking out the NANDroid Manager  application that is now available to install since you have rooted your device. Others who are more interested in changing up the operating system might be interested in checking out what the Xposed Framework  is all about.
When you couple Xposed with the NANDroid Manager application, you are talking about two of the most popular reasons to root a device, so hopefully that gets you started in the right direction on your quest for device perfection.