Hide volume and brightness icons

Good answer here from interestinglythere

http://apple.stackexchange.com/questions/16849/how-do-i-disable-the-volume-control-overlay

Hold up, don't modify important system files! Mac OS has a nice way to start/stop services without doing permanent damage.

To turn off bezels for this user until next login: launchctl unload -F /System/Library/LaunchAgents/com.apple.BezelUI.plist

To undo, change unload to load, or just log out and back in. launchctl load -F /System/Library/LaunchAgents/com.apple.BezelUI.plist

For macOS 10.12 Sierra: Disable System Integrity protection, then: launchctl unload -F /System/Library/LaunchAgents/com.apple.OSDUIHelper.plist Don't forget to enable System Integrity protection when you're done.

I used this method

To turn off bezels indefinitely for this user: launchctl unload -wF /System/Library/LaunchAgents/com.apple.BezelUI.plist

For macOS 10.12 Sierra: Disable System Integrity protection, then: launchctl unload -wF /System/Library/LaunchAgents/com.apple.OSDUIHelper.plist You can now enable System Integrity protection again -- your settings will persist.

To undo, change unload to load. launchctl load -wF /System/Library/LaunchAgents/com.apple.BezelUI.plist