訂正する is correcting the wrong word, sentence or what one’s talking. 正す is correcting the mistake of one’s thinking, action or custom.

I agreed that "訂正する" is correcting the remarks that you made or written materials like emails and articles that you wrote. "正す” is a general term that means to correct. 不正を正す。襟を正す。 不正（ふせい）means injustice. "襟"(えり) literally means "collar" and "襟を正す" means to straighten up or tidy oneself up.

訂正する: correct information published already. 　発言を訂正する。記事を訂正する。 正す: straighten up or point out someone else's mistake. 　間違いがあったら正してください。姿勢を正す。