Complex sentence: The opera libretto was submitted to the censors in January 1836 who required the title to be changed to "La Esmeralda" and all references to Claude Frollo as a priest to be removed.
Split into simpler sentences: The opera libretto was submitted to the censors in January 1836. They required the title to be changed to "La Esmeralda" and all references to Claude Frollo as a priest to be removed.