To migrate an existing user account to an organization:
Create or retrieve the username of a new personal account. You'll add this account as an "owner" for the new organization during the migration process. If you already have another account, write down your username.
Sign in as the account you wish to migrate and visit the migration page.
Put the username of the personal account you wish to make an owner of the organization into the username text field and press "Migrate".
You should now be logged out and receive a confirmation email with the personal account you migrated to.
Now, sign in with your personal account. If you visit you settings page, you should see your migrated organization available to administrate.