Below is the help page which will show you how to change your eBay email address.
http://pages.ebay.co.uk/help/account/updating-registration-information.html
Below are the points to change your PayPal email address.
If you no longer have access to the email addresses for your PayPal account, you will still need to log in using your registered email address and password in to your PayPal account. This is how the PayPal system recognises you. After you log in, you can change the email address you use to sign in with by going to the Profile subtab and clicking the Email link.
If you cannot successfully log in using one of your registered email addresses, you can regain account access by confirming your identity.
Here's how:
-Go to the PayPal homepage at https://www.paypal.com.
-Click Forgot Your Password?
-Enter your email address and then enter the characters in the security text box.
-Click Submit
-Click the I no longer have access to this email address link
-Confirm your identity by choosing one category and filling in the correct information. If you don't remember your security questions and you have registered financial information on your PayPal account, you can complete the financial information field.
-Click Submit
-Follow the directions to complete the password recovery flow.
Most Important:
Also, if you have successfully changed your PayPal address, then please remember to update it in the 3rd step of your "Sell Your Item" form while creating a listing to sell on eBay, under the Payment method section.