After a book is rendered, there will be a series of output files and directories created in the book root directory, typically including *_files/, *_cache/, _book/, and some HTML/LaTeX auxiliary files. These filenames depend on the book configurations. This function identifies these files and directories, and delete them if desired, so you can rebuild the book with a clean source.
clean_book(clean = getOption("bookdown.clean_book", FALSE))
Whether to delete the possible output files. If FALSE, simply print out a list of files/directories that should probably be deleted. You can set the global option bookdown.clean_book = TRUE to force this function to delete files. You are recommended to take a look at the list of files at least once before actually deleting them, i.e. run clean_book(FALSE) before clean_book(TRUE).