This really depends upon how your listing information is being submitted to us. Assuming that your listings are submitted to us by your brokerage, the brokerage name will display on the listing as the link to their website and this information must be changed in the data feed your brokerage provides us with as Deborah said.
Lisa does bring up another option however. If you sign up for Agent Featured Listings you can change this link within your account, provided that Trulia receives your listing information from more that one source. For more information about Agent Featured Listings please see the link below.
Customer Service Representative