romkingz is not responsible if you damage your device in anyway.
Do this at your own risk.
Download SP Flash Tool from here
Download SP VCOM drivers from here
Download and extract Tecno J5 TWRP recovery from here
Download SuperSu.zip from here
Copy SuperSu.zip to your SD Card. (do not put it inside any folder)
Extract and launch SP Flash Tool by clicking flash_tool.exe
Click on Scatter button
Select Scatter file from the TWRP Recovery folder you extracted
Click Download button.
Turn off your device then connect it to your PC
Wait for SP Flash Tool to detect and flash the recovery. (Takes about 10 seconds for process to complete)
When you see tick in green circle, the process is complete. Move on to the next step
Boot your phone into twrp recovery by holding volume up + power button for about 4 seconds
Locate and select the SuperSU.zip you copied in your SDcard
Select Yes to install
Wait for process to complete.
You can always check if your phone is properly rooted with root checker
Credits go to Hovatek for creating TWRP recovery of Boom J5