You can do this by disabling the Bezel UI, here are instructions on how to do so from an answer from another question related to that:
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.
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.
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
.
To turn off bezels indefinitely for all users: sudo defaults write /System/Library/LaunchAgents/com.apple.BezelUI Disabled -bool
YES
For macOS 10.11 Sierra: Disable System Integrity
protection
before doing the above.
To undo, change YES
to NO
, or: sudo defaults delete
/System/Library/LaunchAgents/com.apple.BezelUI Disabled
For macOS 10.12 Sierra: Disable System Integrity
protection,
then: sudo defaults write
/System/Library/LaunchAgents/com.apple.OSDUIHelper Disabled -bool YES
You can now enable System Integrity protection again -- your settings
will persist.
To undo, change YES
to NO
, or: sudo defaults delete
/System/Library/LaunchAgents/com.apple.OSDUIHelper Disabled
Users can override this global setting using the two methods above.
More info: launchctl
is the command-line interface to launchd, the
program that manages services and jobs on Mac OS.
- To reverse any of the above actions, just change
unload
to load
.
-w
means write preference to disk so that it will be used for subsequent logins
-F
means force un/load regardless of the global Disabled
key
You can read more about it in man launchctl
.