¿Cómo deshabilitar las ventanas emergentes de registro de iCloud?

¿Cómo detengo las ventanas emergentes de registro de iCloud en mi computadora?
No quiero registrarme No quiero usarlo.

Suponiendo que se refiere a la pantalla de configuración inicial para iniciar sesión, este script puede ayudar
Fuente: deshabilitar el mensaje emergente de inicio de sesión de iCloud en Lion y posterior

Sin probar, pero si se queja de que Yosemite 'no es mayor que 7', simplemente eliminaría la verificación de versión y la volvería a ejecutar

#!/bin/sh

# Determine OS version
osvers=$(sw_vers -productVersion | awk -F. '{print $2}')
sw_vers=$(sw_vers -productVersion)

# Checks first to see if the Mac is running 10.7.0 or higher. 
# If so, the script checks the system default user template
# for the presence of the Library/Preferences directory.
#
# If the directory is not found, it is created and then the
# iCloud pop-up settings are set to be disabled.

if [[ ${osvers} -ge 7 ]]; then

 for USER_TEMPLATE in "/System/Library/User Template"/*
  do
    defaults write "${USER_TEMPLATE}"/Library/Preferences/com.apple.SetupAssistant DidSeeCloudSetup -bool TRUE
    defaults write "${USER_TEMPLATE}"/Library/Preferences/com.apple.SetupAssistant GestureMovieSeen none
    defaults write "${USER_TEMPLATE}"/Library/Preferences/com.apple.SetupAssistant LastSeenCloudProductVersion "${sw_vers}"
  done

 # Checks first to see if the Mac is running 10.7.0 or higher.
 # If so, the script checks the existing user folders in /Users
 # for the presence of the Library/Preferences directory.
 #
 # If the directory is not found, it is created and then the
 # iCloud pop-up settings are set to be disabled.

 for USER_HOME in /Users/*
  do
    USER_UID=`basename "${USER_HOME}"`
    if [ ! "${USER_UID}" = "Shared" ] 
    then 
      if [ ! -d "${USER_HOME}"/Library/Preferences ]
      then
        mkdir -p "${USER_HOME}"/Library/Preferences
        chown "${USER_UID}" "${USER_HOME}"/Library
        chown "${USER_UID}" "${USER_HOME}"/Library/Preferences
      fi
      if [ -d "${USER_HOME}"/Library/Preferences ]
      then
        defaults write "${USER_HOME}"/Library/Preferences/com.apple.SetupAssistant DidSeeCloudSetup -bool TRUE
        defaults write "${USER_HOME}"/Library/Preferences/com.apple.SetupAssistant GestureMovieSeen none
        defaults write "${USER_HOME}"/Library/Preferences/com.apple.SetupAssistant LastSeenCloudProductVersion "${sw_vers}"
        chown "${USER_UID}" "${USER_HOME}"/Library/Preferences/com.apple.SetupAssistant.plist
      fi
    fi
  done
fi