Earthlight Public mode
It is necessary to specify which user/s or groups of users should no longer use a typical Earthlight interface and instead switch to Earthlight Public mode. This can be enabled via the Users and Groups tool (Administration tab).
In the User or Group settings window navigate to the Advanced tab and tick the Earthlight public mode option.
Earthlight Public layout
Because Earthlight Public is missing all of the tabs which can be found in Earthlight in the top section of the screen, its UI will depend on the configuration made in both Map Layout: Sidebars and Maps Layout: Controls
With some time spent on adjusting the sidebars and map controls, you can make sure that the Earthlight Public will best feat its desired purpose and provide only needed tools for public users.