If you have a screen lock (PIN, pattern, or password), enter it.
If your Huawei P9 Lite L21 has a Google account on it, you must know that password after the reset, or the phone will lock itself. This is an anti-theft feature. How to Hard Reset HUAWEI L21 P9 Lite
The phone will reboot and erase everything. This takes about 2-5 minutes. Use this method if you forgot your screen lock, password, or the phone is stuck on the logo screen. If you have a screen lock (PIN, pattern,
A hard reset will erase ALL data on your phone, including contacts, photos, apps, messages, and accounts. It will return the phone to the exact state it was in when you first bought it. Back up your data before proceeding. The phone will reboot and erase everything
Tap Backup & Reset .
Read the warning list. Tap RESET PHONE .
This is Factory Reset Protection . It's a security feature. You must enter the previous Google account (email and password) that was used on the phone before the reset. If you don't know it, you cannot bypass this legally.