This action cannot be completed because the file is open in another application - Adobe PDF
To find and close the process that has the file open, do this:
- Open resource monitor (Windows +R to open Run then type Resmon.exe)
- Open the CPU tab in the monitor
- Select all processes (not sure if this is needed, you can probably just search for the handle)
- Expand "associated handles"
- Search for the file you need
- Close the process that has the handle
Answer stolen from here https://www.reddit.com/r/AdviceAnimals/comments/2dvbva/the_action_cant_be_completed_because_the_folder/cjtmywc
It turns out that I could not delete the PDFs because they were open - in the file preview window in Windows Explorer! Turn off file previews in Windows Explorer if you run into this issue with PDFs that you cannot delete.