How do I remove beta from my Apple Watch

As described here: https://support.apple.com/en-us/HT204641

Remove the beta profile from your iPhone before you update:

If you installed an iOS or watchOS beta or developer seed

Before you update, remove the beta profile from your device. To view and remove profiles:

• Open the Watch app on your iPhone and go to General > Profiles. Tap the beta profile you want to remove, then tap Delete Profile. Enter your iPhone passcode if requested.
• Go to Settings > General > Profiles & Device Management on your iPhone. Tap the beta profile you want to remove, then tap Delete profile. Enter your iPhone passcode if requested.

To continue using the public beta of iOS, you can install the beta profile again.

If you have the iOS 3.0 beta on your Watch you must be a developer and you need to go through that website in order to have your Apple Watch replaced or reset at an Apple Store. You cannot roll it back yourself.

From other submissions I've read, it appears you can't: only Apple can, and that requires for you to send in the watch. Consult developer website.

You can do a reset yourself.

If you have a backup prior to the Beta installation, you can restore that one. Otherwise you can install it as a "new" watch. The last official non-beta watchOS will be installed.