Delete / Uninstall iTunes on macOS High Sierra (v10.13)
I'm pretty sure you have to disable SIP to uninstall pre-installed apps.


  System Integrity Protection is a security technology in OS X El Capitan and later that's designed to help prevent potentially malicious software from modifying protected files and folders on your Mac. System Integrity protection restricts the root user account and limits the actions that the root user can perform on protected parts of the Mac operating system.
  
  System Integrity Protection includes protection for these parts of the
  system:
  
  • Apps that are pre-installed with OS X