In order to hard reset a CHUWI V89, you should perform the following steps.

Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
CHUWI V89 device will be brought back to the default configuration of a brand new device.

1. First, press and hold the Power button until the phone is turned on.

2. Next, go to Menu > Settings > Change PC settings > Update and recovery.

3. To continue, select Recovery.

4. And then select Remove everything and reinstall Windows.

5. When asked to, select Next. Done! Hard reset should be over in half a hour.