How to remove the sidebar in Apple Preview (presentation mode)? Preview suddenly displays a sidebar on the left-hand side in presentation mode. I do not know how to disable this.

This answer mentions

Always Show Sidebar


in the View menu, but this does not seem to exist in Preview version 10.0.

Update

Even in full screen mode, I do not find this item in the View menu. This is what I see:
While Preview is in full screen, the option is available from the View menu and toolbar button.
The app must be in full screen for these to be available.