Disable Notification Center on OS X Revision as of Sunday, 20 December 2015 at 19:57 UTC
# Disable permanently
sudo defaults write /System/Library/LaunchAgents/com.apple.notificationcenterui KeepAlive -bool false
# Enable
sudo defaults write /System/Library/LaunchAgents/com.apple.notificationcenterui KeepAlive -bool true
# Kill now
killall NotificationCenter