ADB tool. Official Android updated device that is rooted. TWRP recovery. Download SuperSU APK latest version. Make sure the device is connected to the PC. If done, follow the steps as follows.
Step 01: Boot the device into bootloader
Step 02: In the prompt type as "fastboot flash recovery.img"
Step 03: Let flashing recovery.img, and switch to the recovery mode
Step 04: In the TWRP, continue to “advanced” >> “ADB sideload” and swipe to continue
Step 05: Sideload SuperSU download latest version
Step 06: Let process and reboot making SuperSU Pro successfully installed