In the case, you run into issues in starting your Mac or Macbook after the El Capitan re-install, you may have to check some of your kext settings if you hadn’t already taken care of it prior to the beta install.Restart your Mac and you should be all set to go. At this point, you have erased macOS Sierra and re-installed El Capitan.Click Continue and follow the instructions to reinstall OS X and your backed up files.Select the backup you want to restore from.We are assuming that you had made a complete backup before installing the macOS beta on your machine.

From your OS X Utilities menu, click Restore from Time Machine Backup. Invoke Recovery mode while the Mac is starting up by pressing together the Command + R keys.Re-install OS X from OS X utilities and choose the OS X El Capitan Installer.once the process is complete, restart the Mac.Now that the macOS Sierra has been erased from your drive, you will need to re-install the OS X El Capitan. Type in Macintosh HD for the name as Mac OS Extended from the format list and then choose Erase.Select the indented volume name of your startup disk from the left side of the Disk Utility window, then click the Erase tab.Select Disk Utility from your OS X utilities.This launches your Mac into the recovery mode

Hold Down Command +R keys together upon hearing the chime and hold the keys till you see the Apple logo appear on the screen.

Mac osx el capitan vs sierra