For files that are stored on Zotero’s servers, if I select the more info icon on a specific entry, I have two methods of deleting a downloaded PDF. Swiping right on the PDF file at the bottom of the entry provides an indication of being able to delete the file (I assume from local storage) but does nothing. Clicking and holding on the PDF file causes a delete menu to pop up, which does remove the file from local storage. Not sure if this is the expected behavior, nor if it is the intention for both methods to only remove the files locally (this is not 100% clear from any documentation/ wording of the menus).