Removing Apple ID from inherited Apple Watch Series 5

OK, so I bought an Apple Watch off of Facebook marketplace. The original owner is dead. The person I bought it from is the third person that’s had it and he hasn’t had a charger for it for a while so he had no idea if there’s an Apple ID on it or not and I got a charger for it and there is an Apple ID on it since the original owner is dead. I have no way of proving he’s dead because I don’t know if it’s a male or female I don’t know where they live or what and I can’t do anything with the watch. Can somebody help me figure out how to remove the Apple ID because this is a gift for my brother and I can’t do anything with it unless I get the Apple ID removed.

[Re-Titled by Moderator]

Original Title: Apple Watch Series 5