Answer:
That case is simple..As the word defines itself..
Direct discourse-that is, a direct quotation or a direct question-means the identical words the writer or speaker used; as,- "I hope you have not killed him?" said Amyas.-Kingsley.
Indirect discourse means reported speech,-the thoughts of a writer or speaker put in the words of the one reporting them.
Therefore to change direct discourse to indirect discourse it to simply REPORT what the speaker directly says or the writer wrote.In other words, paraphrase the words so as to avoid using QUOTATION MARKS..