Not sure what made this fail, but here you go.
how fails? curl -XDELETE -H "Content-Type: application/json" -u koha:koha http://kohadev-intra.mydnsname.org:8081/api/v1/biblios/3 "DELETE /api/v1/app.pl/api/v1/biblios/3 HTTP/1.1" 204 - "-" "curl/7.68.0"