Please note, before reset to factory settings you must log out of google and Huawei ID. Otherwise, after a reset you need to enter data for previously established accounts. If you don't know them, then after a reset works FRP lock.
To reset to factory settings the Huawei Honor P20 do the following:
Turn off the phone
Press and hold both "Volume +" and "Power"
As soon as you see the logo "Honor" release "Power" button and continue to hold "Volume +"
After load the EMUI recovery menu, release the button "Volume +"
In EMUI recovery with volume buttons (or tap the screen) select "wipe data/factory reset" and confirm your selection by "Power" button
Then write "yes"
In the next menu, again select "wipe data/factory reset" and confirm your selection by "Power" button
After reset, select "reboot system now" and your device will reboot with the factory settings
