I know with my daughter's kindle fire 5th gen you hold down the power button tell it turns off. Approximately 20 sec. Once it's off all the way hold the power button and volume down button at the same time. As soon as the amazon emblem pops up let go of the power button only make sure your still holding the volume down button. After a couple seconds let go of the vloume button when a menu pops up giving you the option to reset,factory reset and a couple other options. Scroll down with with the volume keys and press the power button on factory rest. This will take a second and you will get to another menu that says no for the first couple and then yes factory reset. Scroll down to yes and press the power button again. Then you'll be back to the first one and you press the reset option.
I know some androids have a different combination of keys to get to that menu. It might be different for yours but it's always a combination or power and volume sometime with the home button of there is a physical button and not just one on the touch screen. Let me know if that works if not message me the model number and I'll figure it out for you. On most though you will still need a password when it gets to the activation screen if you had a screen lock or fingerprint lock.