How to erase All the data in my 7-inch Xtouch x708 tablet?

So my friend gave me a 7-inch Xtouch x708 tablet. It's Second hand, so it has some useless apps, some photos and videos, and many more. I want my "Second hand" tablet to be brand new. Therefore, I want to delete All (AS IN ALL) the data in my tablet. Deleting all the data in my tablet makes me feel it's like brand new! But the question is, How can I delete all the data in my tablet? Just like in the Apple devices (like the iPhone), to delete all data in my apple device to make it brand new, I have to connect it in the computer and restore it.

So how can I delete all the data in my tablet?
So far, I have tried going to the Settings > Backup & reset > Factory Data reset.
But it didn't work. When I pressed the "Factory Data Reset" button, it turned off, then on again, and then the language and the background changed. But the apps, the photos and the videos, and all the useless items didn't go away.

That's what I tried. So please help me, because I'm not familiar of the Xtouch tablet.

For factory resetting your Android device, turn off the device. Now, turn it on by holding the 'Home screen', 'Power screen' and 'Volume Up' button simultaneously. This will cause the phone to show up 'System Recover' screen. Scroll down the tablet until you find the option for 'Factory reset'.It will ask you for confirmation whether you really want to factory reset your device. Once you have given confirmation, it will inform that all the data present in the device would get deleted. After you tap the option 'Yes', your tablet will will have the factory image on it again.