I'm using macOS Mojave version 10.14.1 (18B75). In the past few days, 'Desktop' has appeared in my Favourites sidebar in Finder.
'Remove from Sidebar' is an option if I right-click the item:
If I click this, the item disappears for a fraction of a second, and then reappears.
The same thing happens if I try to remove the item in the Finder Preferences:
And, unlike one solution offered on Ask Different, toggling my User folder in the Finder Preferences doesn't solve the issue.
How can I make Desktop disappear permanently?