Just finished the c7 to c8 migration, and except for a few minor hiccups, everything seems to be working fine. I plan on leaving the old c7 powered down and untouched for a week or so just to be paranoid.
At some point, I want to reuse that old c7, maybe as a hub to run any "cloud apps". Question is, where is the option to do a factory reset on old old c7? I really don't want to bring it up now and possible screw up my zwave, so I figure a factory reset when I'm ready to reuse it is probably the best.
I want to do the same and went to Diagnostic Tool earlier and didn't see anything about a hard reset; only soft. Soft doesn't delete devices and I don't want to open every device's admin page to delete.
If my understanding correct, this cleared the databases, but not the Zwave or zigbee radio (that is what that highlighted line is telling you). You must still go into zwave and zigbee details and reset the radios. If you have both of your hubitat boxes powered on with the same radio databases, things are going to go bad quickly.