my previous device doesn't show in "find my iphone"

[VALCRA93]

I sent my iphone 6 to verizon as a trade in but had not been able to deactivate it before I sent it.

They sent me a message that I can deactivate it using the "find my iphone" website, but when i sign in

I don't see that device on my list of devices.  How can I deactivate it as requested by verizon?

[vzw_customer_support]

Once a device is removed from your iCloud account, the Find My iPhone feature will automatically be removed. For more information, you can contact Apple, as they alone are in charge of the iCloud.