“This action cannot be completed because the file is open in another program. This is the message I was receiving when trying to delete some PDF files. It took me a full five minutes but there are tons of comments about this on Adobe’s website. The solution is simple and it doesn’t seem to be related to Adobe in any way.
If you have the preview pane open then close it. Then the PDF files are unlocked and can be moved or deleted.
I said it would be a simple answer.