Resetting a smart device shouldn’t be easy. The Apple Watch is certainly not a cheap gadget, so Apple will surely add more security features to it. As iDownloadBlog has shown on YouTube, it is easy for a thief to reset an Apple Watch that is protected by a passcode. Once that happens, pairing the watch with a new phone is easy.
These guys were able to reset an Apple Watch that was paired to an iPhone 6 Plus and pair it with an iPhone 5s which was signed in using a different Apple ID. It will be interesting to see how Apple fixes this issue. Let’s hope a Watch OS update fixing this is already in the works.[Source]