Instead of changing my email I made a new account?

I don’t know, I have been out of it for weeks, and instead of simply changing my email address on my account, I made a whole new account. Typical Amy. I even placed an order without knowing I had a whole new account. Obviously, I don’t want to lose my old account (this one), but how do I change the email address to the new address now? Do I delete my new account? Gosh, my head hurts just thinking about all this.