How can I make the red exclamation mark on my apple watch go away?

See this --> If you see a red "!" on your Apple Watch - Apple Support but the reality is you will most likely either need to send the watch to Apple for service or take the watch to your local Apple Store Genius Bar for service in person.

By sending it in for a mail in repair if the force restart doesn't work;

If you see a red "!" on your Apple Watch