You are right, unfortunately I can’t change my original statement. Glassdoor doesn’t directly take payment for taking down reviews and I was wrong in implying that.

However, there is an inherent conflict of interest here because Glassdoor makes money from employers and not users. I can’t imagine that this doesn’t impact how reviews are taken down.

Glassdoor absolutely does remove approved negative review without explanation even if it's not for payment. Their customer service is pretty bad and incompetent too. Most of the reviews that remain are utterly useless. Whether they do it for money or other reasons is besides the point.