$ make help
Cleaning targets:
clean - Remove most generated files but keep the config and
enough build support to build external modules
mrproper - Remove all generated files + config + various backup files
distclean - mrproper + remove editor backup and patch files
......
或者直接看Makefile里面关于mrproper和distclean的部分, 这两个应该都可以删除config文件.