I'm new to blender so still figuring things out. I need to basically fill in the cylinder so that it no longer exists. I want to close up the half cylinder on the left, remove the edges in the center, then close up the wall on the right that's currently cut into with the half cylinder indent. I tried deleting vertices and edges, but it seems that no matter what I do it really messes with the design or destroys the face.
Also, are the edges connecting cutouts in my object necessary? Any way to remove them? They seem to complicate making faces.