What is legal or not legal in your state can only be answer by a lawyer practicing in your state.
Sending the person a certify demand letter to removed the property in question in some reasonable time frame or you will consider it abandoned might be a starting point.
Still a whole group of questions comes to mind as in what agreement did you have to start with concerning the property. Was this part of a rental agreement or was the property there for repair works and on and on.
You really need to run this by a lawyer.