Why were some columns from Rani ki Vav removed in the 18th century?

The columns from the top story of Rani ki Vav were removed in the 18th century to be repurposed for the construction of a nearby stepwell known as the Bahadur Singh ki Vav.1

While Rani ki Vav is celebrated today as a significant stepwell and a World Heritage site, it remained buried under sand and mud for nearly a millennium following ancient flooding. During the 18th century, the long-exposed columns on its upper level were taken to facilitate the building of the newer structure.1