@Pengertian: The steps can differ depending on your model and current Android device, however you should start in Settings (Apps > Settings (cog symbol)) then:
- Settings > Accounts > Backup and Reset (Android 4.0)
- Backup and Reset > Factory Data Reset (Android 5.0 to Android 6.0)
- General Management > Reset > Factory Data Reset (Android 7.0 upward)
Remember to backup your device to avoid losing your personal data. If you're unsure how, check out Smart switch for PC or Mac via the link below.
https://www.samsung.com/us/support/owners/app/smart-switch