Google Home Mini has a reset button at the back
1. Long press the reset button
2. Release the button when you hear the confirmation sound. Wait till reset.
3. The same process will have to be done on Google Home Max as well.
If you have Google Nest Mini. And reset button is not given. So the reset rule is different. let's know
1. open themicrophone mute switch
2. Touch and hold on the top of the speaker
3. When you hold, four LED lights live.
4. Keep holding until the speaker hears this resetting sound