In order to hard reset a Philips S308, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Philips S308 device will be brought back to the default configuration of a brand new device.
1. Hold down the Power button until the device turns off.
2. Now press and hold Power and Volume Up buttons.
3. Let go of both buttons held when the Android logo pops on-screen.
4. Now is the time to select Wipe Data/Factory Reset. To do that, use Volume Down to scroll to the option and Volume Up to choose it.
5. Continue by selecting, in the same way as above, Yes - delete all user data and Reboot System Now.
6. Voila! The hard reset process is now complete. Good job.