A way to reset your phone with initial setting is called Factory Reset.

Android devices make it easy to return your phone to factory settings. To do so, go to Settings > Backup & reset > Factory data reset.
But, If you forgot the password or pattern that locks your Android device, or a child entered the wrong password, pin code, or pattern enough times that it's now locked, this article will help you.
 Whatever the reason, if you are unable to reach your phone settings then you have to perform a Hard Reset to unlock your Android phone. Hard reset or Hard Reboot is quite easy and can be performed on locked devices but it will erase all your files and data.
 To perform the Hard Reset follow the following steps.
1. Hold the Volume Up and Power button simultaneously (for Samsung Galaxy devices, hold Volume Up + Home + Power).

2.Hold the button combination until you see the word Start (on Stock Android). Samsung devices will load straight into recovery mode.

3. Use Volume Down to scroll down to “wipe data/factory reset” and press the Power button to select it

4. Confirm your action and Reboot the device.


That's all.
Thank You.