Trying to erase my apple watch after sent in for trade in

I sent an apple watch series 6 for trade in. I received an email today stating the trade in is on hold due to find my iPhone/iPad is not turned off. I strongly recall the watch was completely erased and removed from the account. Apple sent a link with ‘How to remove from account and erase’, I tried using the erase option via iCloud but it states the device will erase once watch is connected to internet. How do I make this happen when the device is with trade in partner already? What is the best way to reach this team ?