Erasing an SSD

The best method to ensure that data is not recoverable from an SSD is to encrypt it and then reformat it. Once you do that it can no longer be decrypt even if you have the passphrase used to encrypt it. So while the data is still there, it is no longer recoverable at all.

You need to be booted from another source in order to erase the internal drive. So, either boot from an external drive or use internet recovery. Might as well follow these since you need to reinstall the original OS or the nearest to it possible:

What to do before you sell, give away, or trade in your Mac - Apple Support

This is part of the loop I got caught up in being unsure if I should encrypt or not. I think I can use Disk Utility to reformat the drive with encryption. If that works, then I reinstall the the OS and should be good. Did I get that right?

Thanks for confirming this step is key. I did get the operating system installer set up on a jump drive.