Enter the following command line into Terminal by typing it or using copy and paste.
The new Debug menu is available.
Close Safari if it is open and then:
LaunchTerminal.
The Debug menu is gone.
However, the hidden Debug menu remained and even picked up a command or two as Safari development continued.
It was removed completely from OS X Sierra and later releases of the operating system.
Accessing the Debug menu, on the other hand, was a bit more complicated.
