There are a few ways to delete pdf files on Android devices. The first way is to use the File Manager. To open the File Manager, open the Settings app and then tap on the three lines that start with “Settings” in the top left corner of the screen. Then, select “File” from the list of options. Under “Open in new window”, select “Pdf” from the list of files and folders that appear. After you select “Pdf”, a new window will open that will look like this: Now, you can delete pdf files by selecting them from this window and then clicking on the Delete button at the bottom left corner of the window. Alternatively, you can drag and drop them onto another file manager such as Nova or ADB Launcher to delete them more easily.