Plan B: is there a way to close this membership and open a new one?
As far as anyone knows, Apple IDs are immortal and cannot be closed, only abandoned.
The only way to create a new Apple Support Communities name is to create a new Apple ID as I wrote. The problem with that is that if you purchased anything from the App Store or iTunes Store, those purchases stay with the Apple ID used to purchase them and they absolutely, positively cannot be transferred to another Apple ID.
I surmise you are concerned because of your user name's suggestion of a specific geographical location? For what it's worth I have no idea where it is and there are probably many places with similar names. I appreciate the need for privacy though, so I understand your concern.
The email address stored in your profile, existing or obsolete, is not divulged to anyone unless you want it to be.