Google does not allow users to change the Gmail address associated with their Google+/Google account. The first Gmail you created stays with the account even if you deactivate your Gmail address. The only way to get a new Gmail is to create a new account with Google. You will be prompted to reopen your old email address.
This is a poor consumer practice in my opinion. Not many email clients allow you to change your email address, but making a new one is easy. Google makes you have to create an entirely new ACCOUNT. This means you have to juggle around two logins.
We ask that President Obama write a letter to Google asking them to change this consumer practice and allow users to deactivate their previous Gmail addresses but allow them them to create new ones without a new account.