i can’t set up my apple watch because somebody else icloud connect to it and i don’t know it

Hello ~ That is the activation lock. If the person/persons that you bought the Apple Watch from cannot or will not remove it …the watch is basically useless to you. If they cannot/will not remove it…return it and get your money back. We cannot help remove it nor can Apple. Take a look here…

Activation Lock for iPhone, iPad, and iPod touch - Apple Support

Also:

The All Too Common SAD Reality of Buying a Used iPad/iPhone

There is always the possibility that the watch could be stolen as well.

~Katana-San~

Hello again~ Do you know the Apple ID it was set up under? Do you have the receipt for it? Take a look here…

How to remove Activation Lock - Apple Support

~Katana-San~