Sadly done with OCLP... How do I wipe it and install Linux?

I have a 2009 Mac Mini that's been successfully running OCLP for years. But in the last month, it's gone to hell: constant freezing, need to restart, more freezing. The only thing I *really* need from MacOS is a BlueBubbles server. But, in the process of troubleshooting, I've uninstalled BlueBubbles, and now I can't even install it. This machine freezes every time I try.

As much as I would like to get BlueBubbles again, I think I have to give up and convert this machine to Linux, where I'll keep using it for SyncThing and Jellyfin. But what's the process for that? IIRC, by installing OCLP, I can no longer get into recovery. Right? So how do I wipe this and install Linux?

Thanks all