Answer
Youlou resigned due to overwhelming governance opposition. He was faced with widespread protests and political unrest from opposition parties and groups, who were unhappy with his governance. Youlou had been president since 1960, and his rule was marked by corruption, nepotism, and a lack of respect for human rights. The opposition eventually forced Youlou to resign in 1963, and he was replaced by Alphonse Massemba-Débat.