unable to reset homepod through home app

Try a hard reset instead: Reset HomePod or HomePod mini - Apple Support

1. Unplug HomePod or unplug the power adapter for HomePod mini, wait 10 seconds, then plug HomePod back in.
2. Wait 10 seconds, then touch and hold your finger to the top of HomePod.
3. The white spinning light will turn red. Keep your finger down. 
4. Siri will say that your HomePod is about to reset. When you hear three beeps, you can lift your finger.

After you reset HomePod, you can set up HomePod again.