Sign in to your account
Head over to the Account Settings page (blue button at the top right)
At the top of the page, you will see your current email address filled in
Delete the current email address, and enter your new one
Click "Update details"
Note: You may need to log in again on any devices where you've logged in with your old email address.
I want to transfer my players to someone else
Have a look at our handy help centre article with help on transferring players to another account: