Deregister RBR50

So, having taken the plunge and splashed out on the new Orbi RBK852, I would now like to deregister my existing Orbi router and satellite (as I've cleaned and factory reset them, and would like to offer them to another person to use) - since Netgear doesn't seem to offer any support outside of a very limited 90 day window, does anyone have any idea how I might go about doing this?

For clarity (and before someone jumps in asking the usual suite of questions), I've looked at the other posts around this topic, and the only solution I've seen is one of the mods (@DarrenM) offering to escalate internally with Netgear 'support'.

There must be some way of achieving this.

Thanks in advance.

WN