Cannot disable "Dark menu bar" on Mac OS X
I just tested the following under OS X 10.11.5 and it worked.


Go to System Preferences > General and check the [√] Use dark menu bar and Dock check box, then close System Preferences.
Copy and paste the following command line into Terminal, then press enter.

defaults delete .GlobalPreferences AppleInterfaceStyle; killall -HUP Dock



After executing the above command line, the Dock momentarily disappeared and a couple seconds later the menu bar was the default color once again.