Problem removing activation lock

My partner thought he lost his iWatch during our last house move however he has now found it but we are unable to turn the activation lock of on the watch to pair it to a new phone. We don’t have the original iPhone either as we have since upgraded our phones. The watch is ready to be paired but wants an update and in order to do that it said it wants the Apple iCloud password which 8 put in but it’s saying it’s not correct. When I tried to reset it I realised that the email address on the iCloud is not correct either.