How do I remove the bottom spray arm and filter?

In the middle of the arm should be a plastic center piece, turn that piece counter clockwise. Once you have that piece unscrewed , lift the arm off. Check on here for parts, number 4,6 on the diagram show you the filter location. There is also more info on here Good Luck.

I'm referring to the piece that hols the filter in place. It comes from the back of the dishwasher