In order to hard reset a ZTE F103, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
ZTE F103 device will be brought back to the default configuration of a brand new device.
1. Switch on the device by pressing the Power button.
2. Now open the Dialer and enter this code in: *983*22387#
3. Tap Call button to confirm the action. Done!