He needs to change his Battlenet email address, but the account is tied to an email that he no longer knows the login information to (created several years ago). Is there still a way for him to change the email address, or is he just SOL?
He can’t do it on his own, no. The DIY system sends a verification code to the connected email address to verify that it is actually him trying to change his account details.
He’s going to need to reach out to a game master via the support link up top and have some form of ID handy to prove it’s him.