New option in Preferences

I download a lot of stuff from Gutenberg and various PDF files to a folder. I was wondering if an option could be added to the Preferences > Adding Books to delete a book from the Source folder after it has been added to the Calibre Library.

Not essential, but if adding a quantity of books and have to put the job aside to do something else, it would be helpful.

Thanks for any consideration.

Thanks for a remarkably useful piece of software!