If you don't mind digging through the database, you can find it by looking in mdl_files for the record:
- contextid = '9445'
- component = 'mod_page'
- filearea = 'content'
- itemid = '70'
- filename = 'FAQ.pdf'
- filepath = '/'
(If you just search by contextid, you should find it pretty quickly anyway)
Once you have that record, if you want to make sure the file is gone from the server, look at the 'contenthash' field, then use that to locate the file in the '[dataroot]/filedir' directory on your server (within there, it has a directory named after the first 2 characters of the contenthash, then another named after the next 2 characters, then the file - e.g. contenthash= 'a4f146f120e7e00d21291b924e26aaabe9f4297a' is found in '[dataroot]/filedir/a4/f1/a4f146f120e7e00d21291b924e26aaabe9f4297a'). You can delete the file there, then delete any records in the database that have that same contenthash and it will definitely be gone (but there may still be some broken links to it, if you can live with that).
Obviously, be very careful and double-check everything before you do any of the above!