A factory reset in Android device reverts the configuration and settings to a completely getting back to the state when you purchased your device. If you forget the password or pattern that locks your Android device, encounter a serious bug or device tends to perform slower, factory reset is the solution you should adopt.
Note : Factory reset would completely wipe your device data, you should backup data before performing the reset.
How to Factory Reset Your Android Mobile
Launch the system settings through the app drawer or home screen as shown in the image below.
Scroll down and find “Backup & Reset” option.
Now, tap on it and you will observe the factory reset option. Tap on it to get started.
Finally, you will be warned that all of your accounts and settings would be wiped from the device. You just have to proceed by selecting “Erase Phone” to reset your device.
If your device screen is frozen or you could not turn on your phone, you can perform a factory reset using the “Recovery Mode”.
Hold the Volume up + Home + Power buttons at the same time
Once the Android recovery mode appears, select wipe data/factory reset with the volume keys and enter with the power key.