I have followed a number of videos, but they all seem to have a copper (?) stem. At this point I'm up to some plastic piece that has no notches (namely around the metal piece) to use a wrench on.
Where do I go from here? I'm thinking that I would pull it out, but don't want to risk it without being sure.
It is leaking, so I'm probably looking to replace more than just the knob.
[EDIT] I went to Lowe's and they cannot help me without knowing the brand. What would be a way to determine the brand? I do not see any labels, here are more pictures: