How to remove your Instructables account
In the FAQ you can read this is only possible by PM’ing an admin or e-mailing the site with your request:
info [at] instructables.com
See the FAQ question: http://www.instructables.com/community/how-to-delete-instructable-account/
Helpful Trick: Removing online data
Helpful Trick: Remove third-party logins
If you signed up for Instructables using a third-party login such as Facebook or Twitter, you probably want to revoke all access from Instructables. Click here to find out how.