You can perform factory data reset as follow.
Before you begin
When you perform factory data reset, all data will be removed.
Please kindly backup the all needed data before the reset.
1. Tap to [Setting].
2. Go to [Backup and reset] - [Factory data reset]. (Android 4.4.2)
Go to [General management] -[Reset] - [Factory data reset]. (Android 7.0)
* Make sure!
Depending on each region and maker, the images as below may be different from yours.