Depending on the current mode, one of the items will be available:
Under the Easy-to-use Mode the item Expert Mode will launch the expert mode of GREAT-ER. All standard menus and tools, etc. will appear as well as the project window. The GREAT-ER menus are appended behind the last menu of ARCVIEW and are only visible when a view window is active.
In the Expert Mode the Easy-to-use mode command sends users back from the expert mode to the easy-to-use mode. All additional menus and some tools, etc. are removed.
Please note that many changes, such as new themes added to a view
are not reversible and these will still be active.
This is usually your intention but, if not, you have delete them manually,
either using the expert mode or the menu item Display /
Remove Themes. Read there for additional information.