How to Clean Install OS X El Capitan on a Mac
Some Mac users may like to perform what is known as a clean install with OS X El Capitan. Basically, a clean install involves erasing the Mac drive and starting fresh with a new installation of OS X 10.11, and users who opt for clean installs usually rely on their own personal backups to restore their personal file and data.
While most Mac users are well served by running the normal update process to OS X El Capitan after it has been downloaded from the Mac App Store, this guide is for users who want to start fresh.