The Apple HomePod is one of the easiest smart speakers to set up. In fact, we're pretty sure itis the easiest. However, if you need to restart it, that's less straightforward.
If your HomePod isn't responding, we'd recommend trying the unplug-and-plug-back-in routine first - you'd be surprised how often this can solve problems. If that's not doing it, or you want to restart the HomePod because you want to give it to someone else, then you'll need to do a full factory reset.
There are two ways to do this, but before you do either you'll need to disconnect the HomePod if it's in a stereo pair with another (otherwise the reset won't work).
Then, to reset from a connected iOS device, do the following:
1) Open the Home app.
2) Find the HomePod in your devices, press and hold on it.
3) Tap Settings.
4) Scroll right down to the bottom and tap Remove Accessory.
This can be done on the Mac too, so long as you have macOS Mojave installed, which brings the Home app to the desktop. It's a similar process here, except you need to double click on the HomePod in the app, hit Settings and then again, scroll to the bottom and tap Remove Accessory.
How to reset the HomePod on the speaker
Alternatively you can do a reset on the HomePod itself. It's a little more of a process, but here's how:
1) Unplug the HomePod and wait 5 seconds. Plug it in again.
2) Wait another five seconds, then press your finger on the top of the HomePod and hold it.
3) The white spinning light turns red, but keep your finger in place.
4) You'll hear Siri announce that the HomePod is going to reset. Once you've heard three beeps, you can take your finger off.