No it is by default not an option... Maybe the reason is that your account info is associated to GameSpyId, and there are no procedure to update the two databases.
You can actually change your email address but I think you manually need to update your GameSpy account to match the same new email address.
The change email field is present on the Account settings page; it is just hidden. I had to change my email in order to "unregister" it from a deleted account.
I installed firebug (plugin for firefox) -> logged in to my supposedly deleted account -> went to "account settings" -> opened the page in firebug and removed the hidden fields -> BAM! you can "free/change" your email address by entering either fake one or thisaccount@isdeleted.com or in your case - enter your new address.
Do remember to login to GameSpy and update your email address too

Hope this helps
