Disposal sign can only applied for mayor + in your own town , You get trade signs as a resident[next rank from bulider] and lift signs can be made with people that that extracreations and you may donate for that or ask players to make then for you
Disposal signs are a donation feature, I would ask in trade chat. Trade signs are made only by users that are resident or higher. Lift signs are also a feature, you can ask in trade chat.