You can ask to have your Blurtit account deleted by heading over to http:.//www.blurtit.uservoice.com and submitting a request.
This will remove your name and profile from ALL content you've posted on Blurtit, and in a few weeks Google should also stop associating your name with any of your content.
Alternatively, you can go to 'Account Settings" (click on your image on the top right of the page to display that menu). From there, simply edit your user name and profile picture so no-one will know who you are!
Finally, you can continue using Blurtit anonymously if you don't want people to know who you are.
