하면 안 돼요 - You shouldn't do that
오늘 날씨가 너무 더워서 집에(or 집으로) 걸어가면 안 돼요 - The weather is really hot so you shouldn't walk home today
시끄럽게 하면 안 돼요 (or 조용히 하세요) - You shouldn't be so loud
그것을 보면 안 돼요 - You shouldn't watch it
안 좋은 것 같아요... 먹으면 안 돼요 - It doesn't look good... You shouldn't eat it
(그것을) 하면 안 됐어요 - You shouldn't have done that
저기에(or 저 곳에) 가면 안 돼요 - You shouldn't go there
말하면 안 돼요 - You shouldn't say that
걱정하면 안 돼요 - You shouldn't worry about it
아무나 말하면 안 됐어요 - You weren't supposed to tell anyone