Skin modifier HELP!

I created a creature with the skin modifier.

I’d like to be able to clean up some of the geometry of it (such as under the arms and the missing faces under the wings) but Blender isn’t letting me select any of the vertices of the faces, just the vertices that the skin modifier is being applied to. What is the best way to clean the geometry of this image?

Apply the skin modifier to make it real geometry

What do you mean?

*Nevermind, I found what I was doing wrong.

Apply button

Cool creature, what’s it for?