Ok. After much sweating, I did work out a safe way to unplug them when new or whenever: It's best before unplugging the connectors to actually use a layer of protection between the connector and the silver foil thing and on top of the scratch-prone plastic. Like some thick carton or plastic. That way you will avoid hitting the "dents magnet" that foil is or scratch the paint.
P.S.: I still really really dislike the connectors system on the HD800s. It's one of the worst.