Anyone who wears a crown has outgrown childhood.

What it means
Wearing a crown brings weight as well as status, and there's no going back to childhood. Authority comes with the expectation that you have truly grown into it.
Yoruba · West Africa
Source and context
From: Yoruba, West Africa
Source: Yoruba (Nigeria) proverb (Eni daade ti kuro lomode), translation and explanation from "20 Yoruba proverbs and their meaning," Edugist (edugist.org)

The source explains it: grow up and embrace the responsibilities of adulthood. The wording of the meaning is ours.