How do I remove this kitchen faucet?
Found a similar design at the Delta website. The round knurled piece should unscrew. The male threaded section should also unscrew. Apparently some have a hex shape to facilitate installation. Some have an internal female hex shape that is removed by an allen wrench. This allows the retaining plate to be removed. If there is enough room between the backsplash and the spout you could try holding the piece under the sink with a pipe-wrench, vise grips or large pliers and have someone spin the faucet.