How do I disconnect my Apple Watch without the phone on me

Edit -

I see that I am late to the party!

Try this on a browser with a computer;

1. Navigate to iCloud.com from your device's web browser.
2. Sign in with your Apple ID and password.
3. Click on Settings.
4. Select your Apple Watch under My Devices.
5. Click on the X next to your Apple Watch to remove it.
6. Click Remove to confirm.

M1 Mac mini, macOS 11.0.1; Watch, series 5 GPS/cellular, watchOS 7.1; iPad Pro 2nd Gen, iPadOS 14.2; iPad Air 2, iPadOS 14.2; iPhone 12 Pro, iOS 14.2.1; TV 4th Gen, tvOS 14.2  HomePods, audioOS 14.1 and Airport Express w/ Airplay 2