How to change the email address associated with my user name

OK, so my son created an id for use here not realising that I was logged on with one of my dev accounts in the dev centre which annoyingly carries over to here if logged on to other Apple sites, e.g., dev forums or Appleseed.

Now, I don't want his username associated with one of my accounts, so the question is, how can I change this so that it is his Apple ID associated with the user name he created?