sofa cover

Hi, There is a mark on our couch that i'm trying to get rid of. I've attached some pictures of it, we've tried hide soap and this hasn't worked. Simply scratching it with a finger nail doesn't work. Any ideas would be appreciated

Wasn't quite sure what section to post this. I have a really nice curved shape (L shape ish) leather sofa. It was bought when we moved into our house and at the time pets was not really a thought. The kitten we just got does not attack it but running around on the sofa I am starting to see a...