If I'm reading correctly, you have a new email addy which you wish to use on your Ebay account, correct? And now you have 2 accounts, with different email addys? You will not be able to change your old account to the new addy at all.....only 1 acc't per email addy. You will have to close the old acc't. Or close the new account, then after closing change the email addy to the new. Here's how......
http://pages.ebay.com/help/account/closing-account.html
Or, call and talk with them as it does take a few weeks to close the account.