1st: Turn OFF your Huawei mate 9 Pro smartphone.
2nd: Press and hold VOLUME UP and POWER button 3rd: Then select “Wipe data/factory reset” using VOLUME DOWN to scroll option,and press POWER button to confirm.
4th: Browse to option “Yes-delete all user data”,and confirm that with Power button.
5th: After that press Power button to accept option “reboot system now” 6th: Done! Thanks For Watching this video