How to remove your Best Buy account
Contact customer support via phone: 1-800-BESTBUY.
Or drop them a message on the forum: http://forums.bestbuy.com/
Should have been a lot easier, but at least they respond to your request.
Helpful Trick: Removing online data
Helpful Trick: Remove third-party logins
If you signed up for Best Buy using a third-party login such as Facebook or Twitter, you probably want to revoke all access from Best Buy. Click here to find out how.