How do you get rid of the Sidebar. It wastes space. It wasn't there yesterday. Reply to Thanks!

How do you get rid of the Sidebar.  It wastes space.   It wasn’t there yesterday.  Reply to  Thanks!

If you mean the left one: drag the sizing handle to the far left. If you mean the right one: again, drag the sizing handle or click on the chevron top right.

it’s indeed as Jorg above explains, I’ll attach a screenshot: