In order to hard reset a Motorola C139, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Motorola C139 device will be brought back to the default configuration of a brand new device.
1. Turn on the phone.
2. Enter Menu.
3. Now select Settings > Other Settings > Initial Setup > Master Reset.
4. Type in Security Code (1234 or 0000 by default) and press OK. Done.