How to remove the watermark on desktop wallpaper
defaults delete com.apple.dock desktop-picture-show-debug-text;killall Dock
Source: https://discussions.apple.com/thread/5236131?tstart=0
last updated november 2017
defaults delete com.apple.dock desktop-picture-show-debug-text;killall Dock
Source: https://discussions.apple.com/thread/5236131?tstart=0