Discouraging situations, and discouraging comments, leave you feeling discouraged. It is the opposite of 'encouraging'. 'Discouraging' doesn't have anything to do with 'courage' in the sense of bravery. If something is discouraging, you feel less positive, confident or optimistic about it. 'Couraging' is a nonsense word. It doesn't exist. Nor does 'uncourageous'.

Although technically correct, uncourageous and couraging are words I don't think are ever used in English. A discouraging circumstance would leave you discouraged. Instead of "He is uncourageous", I would say "He is a coward" or "He lacks courage". Instead of "He is couraging", I would say "He is showing a lot of courage!".