Press the small side button until the power off screen comes on then when the watch is turned off press the same side button until you see the apple logo.
This thread has been closed by the system or the community team.
You may vote for any posts you find helpful, or search the Community for additional answers.
How do I reboot my watch?
Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.