There are currently 3 duplicate links, one of which I believe is not a duplicate. The question itself is asking, if I were to say something negative about my previous employer how would I go about doing it.
The first 2 dups look fine to me, they are basically asking the same thing. The third dup: Why is it not a good idea to “badmouth” a previous employer? while related, isn't really a duplicate of this question. Can it be removed?