How to permanently delete your Google account, but save all your emails and other data

You can delete your Google account by going to Google's "delete or service your account" page, but you can export your data beforehand.
Wired

How to Delete Your Google Account—After Downloading All of Your Data First

Deleting digital accounts that you rarely or never use not only reduces the amount of clutter in your online life—it keeps you safer too. Every extra account you've got is an extra target for a hacker ...