Go behind your case, like on photos, place your hand on side panel and slide it into your direction.
Cheers.
Oooh! I made it! Thanks a lot, I kept thinking I need to try to pull it to the right, not move it backwards, it works, much thanks! (Also I think I made a small bump on the side panel becasue I dont think there was 1 there originally, oops, well, good that it doesn't matter anyway)