Hide columns on Posts screen
How to hide columns on the Posts screen | Screen Options
Reading the Help Options
Next to Options Screen dropdown is Help, it displays as a dropdown tab under the toolbar also(top right), it displays one or more Help items that are related to the Screen that is displayed in the work area.
Click on the Help tab to expand the Help available for a single Screen, then click the Help hanging tab to collapse the Help display
Screen Options, displayed as a hanging down tab just under the toolbar on the top right of the editor screen, it allows the user to decide what fields are presented in the work area for a given Administrator Editor Screen. Each Screen has individual set of Screen Options available to it.
Click on the Screen Options tab to expand the options available for a particular Screen, check (or uncheck) the desired options, then click the Screen Options hanging tab to collapse the Screen Options.