I NEED TO delete a contact!

I accepted a friend request from someone that I THOUGHT was someone else....well, they're basically sending me pornography, which I DO NOT WANT and I don't know how to delete her! Or him! THE CONTACT! Ive read other answers here, they don't work, it just brings me to a screen with my facebook contacts and  nameless contact. Unless that namess contact is the same as the operson who is sending me pornography, I can't delete a person that isn't in the list! Help, what shoul I do!!!!