Hard Reset ZTE Grand X Max

First method:

1. The device must be power off, so press and hold Power button.
2. Then hold down the Power button to turn on the phone.
3. Choose emergency dial, and type the following number: *983*22387#
4. Then from the menu in front of you choose Erase Everything.
5. Done! Now your phone will restart.

Second method:

1. Firstly press the Power button, until your device is on.
2. From the home screen open Menu and choose Settings.
3. After that select Privacy and tap Factory data reset.
4. Choose Reset phone and select Erase everything to begin hard reset operation.

Third method:

1. Turn off your device.
2. After that press and hold Volume Up + Power button.
3. Release held keys when you see an Android menu on your screen.
4. Then press Volume Down to select option "Factory reset", and press Power button to confirm.
5. Afterwards press Power button to enter option "reboot system now".
6. Good job!

WARNING !
Hard Reset will erase all of your data
All described operations you are doing at your own risk.