I know finaly how its work.
If you login to Battlelog, on the left side go down and you will see "Full Site". Click on it, login to full Site, go to Soldier, XXX's Profile (under your Name, the small Text) and on the right side a litle bit down you see Friends. Click on "view all friends".
Now you can use the "X" to delete Friends that you have by origin. On Console you have to enter the Profile and right you see the small exclamation mark. Click on it and on "remove friend".
