Best answer by JackJ
Unfortunately there's no way to factory reset your Watch using only the physical buttons. I'm afraid in this case you'd have to send it for an inspection to our authorized repair center.
For the UK region you can arrange the service booking via mail chat or hotline (at 08000886700 free of charge of course) via https://consumer.huawei.com/uk/support/
Or if you would like I can also facilitate this for you via PM.
Looking forward to your reply!