list of devices on iCloud

I had an Apple Watch (the old model) which I sold , I erased it before to give to new owner.

every time I check the devices in my Apple ID , the watch appears still in the list of my devices but with the name of the new owner ( apple watch (Arto) ), the device is paired with his iPhone, and signed with his Apple ID ,

I have deleted many times the device from my ID but still keeps showing.

Any hint of what to do?

I tried to post this in Apple Watch discussion but doesn't allow me

but I think it is an iCloud or apple id issue.

Hope u can help.