[Kuram]

I have almost 400 books in my library, and I used the "Add books" function to have them added to a calibre library in bulk. I understand that it creates a new "calibre library" directory and copies the files there and organizes them. My question is, after this is done, is it all right to delete all the files from the host folder? Or do they still need to exist for Calibre to recognize them? I tried googling for the answer but I can't seem to find anything that says one way or the other (or in the user guide either)

Thanks for your help !