Unfortunately, there might come a time in the life of your handset where you will need to perform a factory reset. Please locate the make and model of your handset below, and follow the instructions to see how:
- Before you erase your iPhone with iOS 10, make sure that you sign out of iCloud. Otherwise, your device might remain in Activation Lock. To do so, please follow the instructions below:
- In iOS 10.3 or later, go to Settings > [your name] > Sign Out.
- In iOS 10.2 or earlier, go to Settings > iCloud > Sign Out.
- Then go to Settings > General > Reset.
- Then tap Erase All Content and Settings.
Samsung Galaxy S7
- Swipe down from the top of the screen to pull down the Notification Shade.
- Tap the Settings button. It looks like a gear.
- Swipe up to scroll down on the settings screen
- Tap Backup and reset
- Tap Factory data reset. It's a the very bottom of the screen, so you may have to scroll down to see it.
- Tap RESET DEVICE
- Tap ERASE EVERYTHING
The device will turn off and then restart. When it does, you'll see the initial load screen for the S7 followed by a blue screen with the little green Android robot in the centre. It will take a few minutes for your device to completely reboot itself and launch with factory settings restored.
Credit to https://www.androidcentral.com/how-factory-reset-galaxy-s7