How to remove your Gist account
Bottom right on your settings page: click the removal button.
Direct removal link: https://gist.com/accounts/settings
Helpful Trick: Removing online data
Helpful Trick: Remove third-party logins
If you signed up for Gist using a third-party login such as Facebook or Twitter, you probably want to revoke all access from Gist. Click here to find out how.