That's a great follow up question that I didn't ask them when originally inquiring about NSEC management.

nostr:npub1akngghxzy6d75y8szp6y44u5pxktwy5aj6zh6jl3ncp8d93fj2fq5mfxa8 will you be able to delete your NSEC from ZBD custody once you export it?  And will it be purged from backups? Or once ZBD has your NSEC, will it always have a record of your generated NSEC?