Is my iPhone still connected to iCloud?

I have an iPhone6s that took an heavy blow and now it overheats and shuts down. I don't want to repair it but I would like to remove it from iCloud and sell it as 'spares or repair' but I have limited time to do this before the phone overheats and shuts down.

So far I have down a DFU on the phone to reset it. Now I get Hello, Hola etc welcome the phone turns on. I then went to iCloud and found it offline in 'Find My iPhone' and so I deleted it but it said it will reappear next time it connects to the internet. It's also gone from 'My Devices' in 'Account Settings''.

My concern is the message saying it will reappear in 'Find My iPhone' the next time it connects to the internet.

So is the phone still associated with the iCloud and if so what do I have to do to remove it completely.

Thanks for looking