Cannot uninstall OCLP

Trying very hard to uninstall OCLP (reasons here, but I still love OCLP) but hitting a wall. Can anyone advise? Here's the situation:

• I'm running Monterey and have the latest OCLP installed on a 2009 MacMini, for which the last official support is (I believe) 10.11.6.
• I've tried using the Revert Patch tool inside the OCLP app, but that didn't work.
• I've tried using the MountEFI tool, but I don't see an EFI folder. In fact, when I use the normal diskutil list command, I do not see an EFI disk listed on my drive at all. And it gets weirder...
• When I boot this machine and hold down Option (hoping to boot from the MacOS Install USB drive I've created) the only option that comes up is: EFI. When I click that, I'm taken to another screen showing my normal home drive and then the regular boot process begins.

Can anyone help? I would love to boot from my USB and simply wipe this machine. Thank you