Koolaburra by Ugg girls size 2

I think these may have left the house 4 times! I’m not sure what the stain on the one boot is but I tried to clean it and made it worse. Maybe you know better than me how to get it out! All I know is that shoe went to school and then daycare so it could be anything. The sticker on the bottom of the shoe was put there by the manufacturer and was apparently difficult enough to get off that she just wore them with the sticker.