There’s a simple way to back up your data: get Google to send you a download link via email. This link allows you to download your entire archive. What’s more, this feature is not only relevant for Gmail data but also for all other Google services including Google Calendar, Google Photos, and your browser history. Would you rather save your files to a cloud instead of a local drive? No problem! Google offers the option to save your entire archive in Google Drive, Dropbox or Microsoft OneDrive.
If you have second thoughts after deletion, you may be able to restore your account using your usual email address. But don’t expect your data to still be available. If you deleted your account a long time ago, your emails will typically no longer be accessible. So, it’s always a good idea to create a backup before you delete your account.
If you use your Gmail account via a group (school, college or work), you might not be able to delete it as easily. Contact the administrator of the email group if you have any problems.