How to disable "split view"? Is it possible to bring back simple window maximize button as it was before and when holding option to use split view?
You cannot change that function of Full Screen button to, but there is simple workaround. Go to Keyboard Preference Pane > Shortcuts > App Shotcuts > + > All Applications, and Menu Title to Zoom/Maximise, choose a shortcut of your preference. Now you can use that shortcut to mimic the behaviour of "old" Maximise button.