1. Lets start from turning off your device.
2. Once you've done that hold Volume down, Home, and Power buttons until the reset screen will show up.
3. Navigate with Volume keys buttons and to confirm press Power button and select wipe data/factory reset option.
4. Once you do that, the hard reset process will be completed, congratulations.
2nd METHOD
1. Go to your menu settings and find Back up and reset, then tap on it.
2. Afterwards, you want to choose Factory data reset option.
3. Lastly, you will see a information that your data will be erasedso make sure you have backed up all your important data and select Reset device.
4. And that's it! The phone will now reboot, returning to its default settings.