Lock or unlock Apple Watch Ultra
Unlock Apple Watch Ultra
You can unlock Apple Watch Ultra manually, by entering the passcode, or set it to unlock automatically when you unlock your iPhone.
Enter the passcode: Wake Apple Watch Ultra, then enter the watch passcode.
Unlock Apple Watch Ultra when you unlock your iPhone: Open the Apple Watch app on your iPhone, tap My Watch, tap Passcode, then turn on Unlock with iPhone.
Your iPhone must be within normal Bluetooth range (about 33 feet or 10 meters) of your Apple Watch Ultra to unlock it. If Bluetooth is off on Apple Watch Ultra, enter the passcode on your watch to unlock it.
Tip: Your Apple Watch Ultra passcode can be different from your iPhone passcode—in fact, it’s better to use different passcodes.
Change your passcode
You can change the passcode you created when you first set up your Apple Watch Ultra by following these steps:
Open the Settings app
on your Apple Watch Ultra.Tap Passcode, then tap Change Passcode and follow the onscreen prompts.
You can also open the Apple Watch app on your iPhone, tap My Watch, tap Passcode, then tap Change Passcode and follow the onscreen prompts.
Tip: To use a passcode longer than four digits, open the Settings app on your Apple Watch Ultra, tap Passcode, then turn off Simple Passcode.
Turn off the passcode
Open the Settings app
on your Apple Watch Ultra.Tap Passcode, then tap Turn Passcode Off.
You can also open the Apple Watch app on your iPhone, tap My Watch, tap Passcode, then tap Turn Passcode Off.
Note: If you disable your passcode, you can’t use Apple Pay on your Apple Watch Ultra.
Lock automatically
By default, your Apple Watch Ultra locks automatically when you’re not wearing it. To change the wrist detection setting, do the following.
Open the Settings app
on your Apple Watch Ultra.Tap Passcode, then turn Wrist Detection on or off.
Turning off wrist detection affects these Apple Watch Ultra features:
When you use Apple Pay on your Apple Watch Ultra, you’ll be prompted to enter your passcode when you double-click the side button to authorize the payment.
Some Activity measurements are unavailable.
Heart rate tracking and notifications are turned off.
Apple Watch Ultra will no longer automatically lock and unlock.
Apple Watch Ultra wonʼt automatically make an emergency call even after it has detected a hard impact fall.
Lock manually
Touch and hold the bottom of the screen, then swipe up to open Control Center.
Tap
.
Note: To manually lock your Apple Watch Ultra, you must turn off wrist detection. (Open the Settings app on your Apple Watch Ultra, tap Passcode, then turn off Wrist Detection.)
You must enter your passcode the next time you try to use your Apple Watch Ultra.
You can also lock your screen to avoid accidental taps during a workout. While using the Workout app 
on your Apple Watch Ultra, just swipe right, then tap Lock. When you start a swimming workout, your Apple Watch Ultra automatically locks the screen with Water Lock.
If you forget your passcode
If you forget your passcode, you must erase your Apple Watch Ultra. You can do so in these ways:
Unpair your Apple Watch Ultra from your iPhone to erase your watch settings and passcode, then pair again.
Reset your Apple Watch Ultra and pair it again with your iPhone.
For more information, see If you forget your Apple Watch Ultra passcode.
Erase Apple Watch Ultra after 10 unlock attempts
To protect your information if your watch is lost or stolen, you can set Apple Watch Ultra to erase its data after 10 consecutive attempts to unlock it using the wrong passcode.
Open the Settings app
on your Apple Watch Ultra.Tap Passcode, then turn on Erase Data.
If you have a Mac running macOS 10.12 or later, you can unlock your computer with your Apple Watch.