No security options for external hard disk erase in Disk Utility
MacOS doesn't let you do a Secure Erase on encrypted volumes because there's no point: a single erase will delete the encryption keys; and any residual data on the disk will be meaningless junk that cannot be decrypted.

Multiple zeroing of a mechanical disk can put significant stress on it and shorten its lifespan.

Similarly, MacOS doesn't let you secure erase SSDs, because that's also a pointless exercise: doing the erase doesn't actually make it more securely erased.

Why is a secure erase &#39;not necessary&#39; for SSD&#39;s?