oli tank (under neighbor's property)

I placed an offer on a Fannie Mae (Homeopath) owned home. I had an inspection and oil tank sweep. An oil tank was found but oddly it was on the neighbor’s side of the fence. The fill pipe was on the neighbor’s side and the vent pipe was on “my” side. Looks like all the tank is on neighbors side.
My lawyer is asking seller to remove tank but I’m not sure if that will work - “as is” deal. Lawyer also looking in to previous subdivision of lot.
Wondering if anyone has had similar experience.
This is in NJ.

If the fill opening is on the neighbors property are you sure the tank belongs to the seller or does it belong to the neighbor. If it is the neighbor’s tank and it is encroaching on your lot, I would try to simplify the matter and have the neighbor sign an agreement stating that they are responsible for the tank regardless of the location and remediation.