Issue with changing email address on my account

I have an Apple account with an email that is tied to my internet provider, which I may change. A few years ago I tried to change to a gmail address and I accidentally created a second account. Now because the gmail address that I wish to use is tied to an unused account, I cannot change the email in my existing account to the new one. Looking on line, if I delete the unused account, I can never use it for again for any purpose on apple. So is there any way I can get around this issue, so I don't lose any notifications when my existing email goes away?