How do you unlock Galaxy S5?

Answer 1

As a disclaimer, keep in mind that resetting the Samsung Galaxy S5 may delete most, if not all the files stored. Before performing this, make sure the device is fully charged.

Turn the phone off. Then, press the power button, volume up button, and home button all at the same time. Keep it depressed until you see the Android logo on the display. Using the volume controls, use the volume down button until you get to "wipe data/factory reset". Press the power button, then confirm by highlighting "Yes - delete all user data". Press the power button again. When you see the "reboot system now" option, use the power button to choose it. After it restarts, it should take you back to the phone setup screen.

Answer 2

Before you choose to unlock a Samsung Galaxy S5, ask yourself why you would like to unlock it? Also, what kind of unlocking are you wanting to do? There's carrier unlock (which unlocks the SIM card, allowing to put a different carrier SIM), or unlocking the bootloader, which would allow you to root your phone, change or remove carrier apps, flash a custom ROM (OS), and so on. Most customization that you can do doesn't require unlocking, or rooting for that matter. Also, keep in mind that there are inherent risks on modifying your phone, which in the worst case scenario is that you might "brick" your phone, or render it unusable.

If you are comfortable with going forward with it, you can try the Towelroot app which will root a carrier-based Galaxy S5. If you just want carrier unlock, you can see if your carrier or a 3rd party can unlock it for you for a fee.