http://www.mangago.me/read-manga/fff_class_trashero/
These ones below are mangas but there's no romance (in the genre)
http://www.mangago.me/read-manga/higeki_no_genkyou_tonaru_saikyou_gedou_rasubosu_joou_wa_tami_no_tame_ni_tsukushimasu/
http://www.mangago.me/read-manga/yuukoku_no_moriarty/
The second one may seem like a shoujo but I haven't seen any signs of romance.
The third one is a personal favourite.
The first one has no romance at all unless if you think manipulation is romance. It's also something I read to pass by time
This is a tragedy manhwa. Just dropping it here in case you like angst: http://www.mangago.me/read-manga/an_uncomfortable_truth/?EVDq
Pretty sure that's anything but romance tho.
Manhwa no romance plssssss :)