Why does Ralph say that he wants to give up his chief status in chapter five?
At the beginning of chapter five, Ralph is worried that things are starting to unravel and he feels that they need to have a very serious meeting. He is worried about all this and realizes that he is having trouble thinking through it, that he isn't very good at it. He wishes he was more like Piggy who seems to be able to figure things out so quickly and easily. He doubts his ability to be chief effectively.
And after Jack suggests that they ought to stop having these meetings and just have fun, Ralph's doubts intensify. Ralph cannot understand how to share his vision and the urgency of it with the boys. Piggy suggests that he needs to remain chief because the grown ups would approve and because Piggy understands what Jack's road will lead to.
But Ralph's doubts are not going to be helped by Piggy's assurance because he knows Piggy is no leader and does not have the charisma to revers what Jack is doing.