The way to change flat icon on OS X Sierra

OS X Sierra Change Flat Icon Tutorial

1. Concepts:

System Integrity Protection (SIP)

"Apple has enabled a new default security oriented featured called System Integrity Protection, often called rootless, 
in Mac OS from versions 10.11 onward. The rootless feature is aimed at preventing Mac OS X compromise by malicious code, 
whether intentionally or accidentally, and essentially what SIP does is lock down specific system level locations in the file 
system while simultaneously preventing certain processes from attaching to system-level processes." 
- OSXDaily [http://osxdaily.com/2015/10/05/disable-rootless-system-integrity-protection-mac-os-x/]

2. Why should I care about SIP?

Because in order to change icon (with LiteIcon app), you need to bypass SIP

3. Steps:

- Disable SIP (in Recovery Mode)
  + Reboot
  + Hold Cmd + R right after startup sound
  + Open Terminal (from Top Menu)
  + Type: "csrutil disable" (without quote)
- Using LiteIcon to change icon
  + Get LiteIcon app at: https://freemacsoft.net/liteicon/
  + Get flat icon pack at: http://flaticns.com/
  + Using LiteIcon to replace icon
  + Clear icon cache: "sudo find /private/var/folders/ -name com.apple.dock.iconcache -exec rm {} \;" (without quote)
- Re-Enable SIP (in Recovery Mode)
  + Reboot
  + Hold Cmd + R right after startup sound
  + Open Terminal (from Top Menu)
  + Type: "csrutil enable" (without quote)