How to remove a device from the Apple Health app
Great question, but one I don't think I can answer because I’ve had my Watch for almost a full year and yet, I don't have multiple instances of it appearing in the Sources section of the Health app. Then again, I've restored my iPhone and set it up as new a few times. I hardly ever restore from a backup. Having said that, I *assume* either un-pairing your Watch from your iPhone or setting up your iPhone as new will remove the data sources therein. I couldn't find a delete/remove option.