To secure erase when that option isn't available in Disk Utility. For example, for SSDs. Boot from another disk or recovery mode. Erase the disk encrypted, with a complex key. Fill the disk with zeros. Erase it again, without encryption or with a different key.
Options to fill with zeros
If it is available, use mkfile, otherwise use dd...
I usually write a blog post about once a week. The latest post can be viewed here: Global Zeitgeists: You might just have become a victim of the latest global zeitgeist. (posted 2024-07-05 at 15:02:37). I do podcasts too!. You can listen to my latest podcast, here: OJB's Podcast 2024-04-30 The Fall of Rome: I'm afraid that we really might be seeing the demise of the greatest era in history..