OS10 Applecwatch, is it possible to lock the screen? The raindrop has gone.

How to use Water Lock and eject water from your Apple Watch states: "To open Control Center, press the side button (for watchOS 9 or earlier, touch and hold the bottom of the screen, then swipe up). You can open Control Center from any screen."

Please refer to Use the buttons and screen on your Apple Watch.

Press the side button

• Press to show or hide Control Center.
• Press and hold to use Emergency SOS.
• Double-click to use Apple Pay.
• Press and hold to turn your watch on or off. 

If you have Apple Watch Ultra or later, you can customize the Action button to access your favorite features quickly.

If you haven't updated watchOS, learn how to use the side button. 

If the Flashlight icon is not visible, please refer to Use Control Center on Apple Watch.

Rearrange Control Center

You can rearrange the buttons in Control Center by following these steps:

1. Press the side button to open Control Center.
2. Scroll to the bottom of Control Center, then tap Edit.
3. Touch and hold a button, then drag it to a new location.
4. Tap Done when you’re finished.

Remove Control Center buttons

You can remove the buttons in Control Center by following these steps:

1. Press the side button to open Control Center.
2. Scroll to the bottom of Control Center, then tap Edit.
3. Tap  in the corner of the button you want to remove.
4. Tap Done when you’re finished.

To restore a button you’ve removed, open Control Center, tap Edit, then tap  in the corner of the button you want to restore. Tap Done when you’re finished.

Try that on OS10. No more water drop.