Kelaiya,
Did you add the listing manually or was it uploaded from your MLS or another service like ListHub?
If you entered it manually it may be due to the fact Trulia may employ multiple servers with different databases it may just be the property "deletion" needs to work it's way through the system. If the listing is from an automated feed you may have to remove it from the original source, such as your MLS or ListHub for it to be removed.... more