Homepod reaet

What steps did you try?

You can do it through the home app by removing it or by pressing the top

see here: Reset HomePod - Apple Support (CA)

if you press the top method make sure you count to 10:seconds (exactly) - this is twice during this process.

What do you mean by can’t add it? If it’s been removed from the Home App, it has been reset (all data has been erased) and can’t be used for anything until you set it up again

Set up and use HomePod - Apple Support (CA)

First try a Restart:

Open the Home App

Long press on the HomePod icon to bring up settings, scroll down to the gear icon, tap that, scroll to the bottom to Reset HomePod - then select Restart HomePod 

Try the Reset again .First try pressing the top but before you do plug it in for awhile so it’s not confusing the 10 second sequence it’s trying to achieve for the hard reset.

Then try removing it.