Call your Realtor and have them take care of it. They can contact the listing agent or mark it as sold in Trulia and the website automatically contacts all parties involved to verify that it was sold by them. Your Realtor, is who you have a relationship with and they will probably be glad to help. Also it will give them recognition in Trulia as one who helped sell a home. It is probably just an oversight on the listing agents part.
You may want to call the listing agent and see if they can remove them from their MLS system. This system often feeds Trulia which then will remove them from Trulia. Now that it's sold, it may not work though.