Answer by jmpp

It appears to be impossible, as apparently your e-mail address is your Asset Store login. Check this out: http://forum.unity3d.com/threads/102628-How-can-I-change-the-email-in-the-Asset-Store-profile So, in short, what you have to do is create a new account with your new e-mail address. The one thing I'm gonna have to find out manually is if your download history is preserved across accounts... here's hoping!