N.Y. landlord obliterated dozens of graffiti murals. Now he owes the artists $6.7 million.

From the elevated 7-train, millions of people passing through Long Island City, Queens, could spot the massive warehouses. Five stories high, the buildings took up most of a city block. But that’s not the only reason the complex was hard to miss. Its bright yellow walls were covered with hundreds of graffiti murals: colorful bubble …