I wanted to share my experience because there were no existing topics to cover this.
I moved homes and took my Sonos One SL with me. I created a new wifi network, so obviously I knew the Sonos One SL would not connect to the new network. I simply figured this would be an option inside the sonos app to change the network. It was not.
First, I tried attempting to connect and the Let’s Fix It option was coming up at the top. I went through the instructions, finding the sonos product, and then attempting to connect to new network. No luck.
Second, I tried a master reset of the sonos by holding down the join button while reconnecting to power. Sonos was reset, but would not connect to my phone (apple iphone 12).
Finally, at the suggestion on here through another topic, someone suggested removing the app. This actually worked for me.
So, in conclusion, solution is to factory reset the speaker, and then remove app and then claim the factory reset sonos product. VOILÀ!