How change that?
How change the inicial Gmail?
I have the same question
I believe you will need to change the E-mail that is connected to your Playstore or whichever App store you use. Though you might try Disconnecting the e-mail, exiting the game, re-open game and enter new e-mail route.
You can do what I did
Submit a ticket to perblue
Full disclosure: I only asked them to remove it, as it was an email address I no longer have access to.
But I’m sure they could fill in the field with something else