I'm trying to remove my bathroom sink stopper so that I can clean out the drain.
I found these instructions for doing so but they talk about a pivot nut that can be loosened. Under my sink, in the place where a pivot nut is shown in the diagram on that link mine has this round fitting with grippy edges. I tried to use a needle nose pliers on it but it just slides and won't grip and I can't get leverage to turn it and loosen it.
What is the correct tool for loosening this fitting? Sorry I don't know much about hardware or plumbing so I don't know the proper term for the round fitting.