You can toggle Project, column/Workflow state, or Epics on and off by clicking on their checkbox or icon.
To select just one, you can hover over it and select "Only" from the context menu.
To show or hide all items in a section, click the drop down next to the section name and click "Show All" or "Hide All". You can also use the Projects or Epics sections to perform many of the same actions you carry out on the Projects and Epics pages.
By default, Clubhouse will only display unfinished Epics in an expanded view. In order to also view finished Epics, scroll to the bottom of your Unfinished Epics list and click "Show Finished Epics".
You can also narrow the list of visible Epics on the Stories page down to only Epics found in currently selected projects, only the Epics you are following, or only Epics that are in progress or unfinished.
You can do this from the context menu of the Epics section in the lefthand column or from the Quick Filters section