I don’t see the editor option in appearance, admin. I need to paste the tracking code in the footer. I have never checked it before. So no idea it was there and vanished or not. I am using an ipad guys. Please keep that in mind while answering.
You cannot edit your theme files. You cannot change the appearance of most themes here without the Custom Design upgrade and even then you can only change the CSS, not the underlying way the theme works.