After a couple of seconds, press Power button.
As soon as ASUS logo appears, release the buttons.
Success! The hard reset is done.
Factory Reset in ASUS ZenFone 3 Max - Restore / Delete Data / Format
Hard Reset ASUS ZenFone 3 Max - Bypass Password / Format Data
Hard Reset ASUS ZenFone 3 Max - Clear eMMC / Bypass Passowrd
Hard Reset will erase all of your data
All described operations you are doing at your own risk.