Shell in the kobo, from the root :
sqlite3 -header .kobo/KoboReader.sqlite "SELECT ContentID FROM content WHERE BookTitle is null and ReadStatus = 2 ORDER BY Title;" | grep epub | sed 's!file:///mnt/onboard/!!' | while read f; do rm -f "$f"; done
Shell in the kobo, from the root :
sqlite3 -header .kobo/KoboReader.sqlite "SELECT ContentID FROM content WHERE BookTitle is null and ReadStatus = 2 ORDER BY Title;" | grep epub | sed 's!file:///mnt/onboard/!!' | while read f; do rm -f "$f"; done
Using an online SQLite viewer like https://inloop.github.io/sqlite-viewer/ : list all read books