when trying to delete screenshot.jpg on High Sierra desktop I get error code -43, see screenshot below -
This is unlikely caused by TotalFinder.
Please try to follow this article:
You can find every Issues here on | The Mac Smack
The Mac Smack
The solution to your problem is right here. Follow few steps and I hope your Mac error code 43 will be resolved - http://itechinspector.com/how-to-fix-mac-error-code-43.html