Should an agent remove a sign after sale?

[Greg M.]

A friend recently closed on a vacant land purchase. The property was a large vacant parcel that is adjacent to the public street. There is a second parcel that is further in and does not touch public street (there is an access easement to get to the property) that is still for sale. The same listing agent had the contract for both parcels and had a huge sign advertising the parcels for sale. It is not located adjacent to the easement to get to the interior property.

My friend has asked the agent to remove the sign, and suggested that the agent put a small sign adjacent to the easement road, with an arrow, pointing down the easement road and then install his big sign at the property boundary.

So far, the agent has refused to take his sign down and is ignoring most of my friend's e-mails.

The sign has been up 2 years. Based on the listing price of the second parcel, my friend expects it may take 2-3 years to sell. So this is not a short 30 day problem.

My friend's questions are: Should the agent take his sign down off of my friend's property?

How can my friend enforce this?

This is a vacant parcel in another state, my friend is not able go deal with it himself.