if everything came back, you probably haven’t stopped the HA Core.
→ login into your CLI
→ stop HA Core
→ remove config / custom_components / database / etc
→ start HA Core
That should it be.
Anyway - I don’t see the benefit of having a factory reset button - except, that this could be executed by mistake - or by a flaw…
Wiping the SD Card for those who run HA on an PI - and reinstall everything would still be the safest way.
For those, who run HA on a Virtualized environment, it’s even simpler… create a new Docker / VM whatever - and done.
You could still backup parts of your old config to restore some configurations.