Unlock bootloader.
Install TWRP recovery.
Boot to TWRP (Go to bootloader screen by Power off, followed by Vol – and Power On button pressed simultaneously, then Power button released; Next Vol – to highlight recovery menu, and press Vol +)/
Install Superuser latest package from TWRP.
Reboot, and install SuperSU app from Play Store.
Also install busybox with Busybox installer by sterricson, from the Play Store.
Joel G Mathew, known in tech circles by the pseudonym Droidzone, is an opensource and programming enthusiast.
He is a full stack developer, whose favorite languages are currently Python and Vue.js. He is also fluent in Javascript, Flutter/Dart, Perl, PHP, SQL, C and bash shell scripting. He loves Linux, and can often be found tinkering with linux kernel code, and source code for GNU applications. He used to be an active developer on XDA forums, and his tinkered ROMS used to be very popular in the early 2000s.
His favorite pastime is grappling with GNU compilers, discovering newer Linux secrets, writing scripts, hacking roms, and programs (nothing illegal), reading, blogging. and testing out the latest gadgets.
When away from the tech world, Dr Joel G. Mathew is a practising ENT Surgeon, busy with surgeries and clinical practise.