You can click the cog icon at the bottom of the sidebar and scroll to the bottom of the customize panel to find the Vertical/horizontal tab setting among other settings for the new sidebar panel including what items you wish to see. You can hide the sidebar by selecting "Show and hide sidebar" for the Sidebar toolbar button. You can click the Sidebar button to open and close the sidebar. You may have to add the Sidebar button to the toolbar if you have removed it.

• https://support.mozilla.org/en-US/kb/use-firefox-sidebar-access-bookmarks-history-synced

Hi cor-el

Thank you for the detailed guide. I am apparently one of the lucky portion of Firefox users that have received the updated sidebar, as noted on the page you link to (Se the note below).

Note: An updated Sidebar is available to a portion of Firefox users, starting in Firefox version 133. See this article for details.

There are no options to remove it. Se screenshots.