[Koha] Biblio deletion

Goodmorning Can anyone direct me to instructions on how to batch delete biblio records. I managed to batch delete the items attached to the records and now I need to delete the records themselves, but I really don't want to do this one at a time for over 1100 records. …Or have I misunderstood the process entirely. Best wishes Ann Murphy Librarian Katikati College amurphy@katikaticollege.school.nz