I don't know the first thing about plumbing so pardon my pitiful vocabulary.
My shower tub has been draining very slowly for quite some time now. I'm almost positive it's hair/gung that has accumulated over time. However, I can't even remove the drain "cover" (not sure what you call it) to clean the assembly beneath it. It's a Price Pfister model and you press one side to close it and one side to open it. There's a "Bath Clean-Out" near the drain, which is just a chrome circle with a Philips screw through the center (I have no clue what it does). All I need to know is how to remove this top "cover." I tried twisting it and simply trying to pull it out, but nothing seems to work. I'm sure it's something really stupid. I've attached a link to some pictures of my drain. Thanks in advance.