Have you gone into the skin details section on the face? If not, click on her head to bring up the head editing options (anywhere works, it'll be the top icon on the menu buttons that pop up). After you press the top button, you should be able to go through the subset of buttons that appear and there should be one where you can find the eyes/brows (sorry, I forget exactly which catagory that scar is in) and you should be able to take it off that way/the x over that catagory.
Alternately, if you don't have a lot of other details (non-default teeth, freckles, additional line marks on her face, etc.) if you hover over that first button, an x should appear over it and you can get rid of it that way. This takes off ALL extra details though, not just the scars. If you have things you want for her, you'll have to put them back on if you do this.
Hope it helps! :)