Removing device from iCloud account

Hello, I bought a refurbished iPhone from a third party vendor. A few months after purchase that iPhone showed error code 4013. Various tech support companies told me that usually indicates the motherboard in the device has gone bad. So I removed the device from my iCloud account before returning it to the seller (or at least I thought I did). The seller says the phone is still linked to my iCloud account, but when I log in I do not see that iPhone 11 Pro listed under devices. Is there a way I can confirm I deleted that phone from the account other than viewing the device list? Of course they won’t refund the device unless it is removed from the account.