Hello ! I’ve sold one of my speakers

Hi ​@domsheldon1 

Welcome to the Sonos Community! Apologies for the delay.

When selling a speaker, do not transfer ownership - this will indeed move your entire system to a new email, rather than just one speaker.

Instead, please factory reset the speaker before handing it to the new owner. You can see the instructions for doing so on our Factory reset your Sonos product help page. The instructions can vary a bit according to the speaker model, and you should end up with a flashing green light at the end of the process.

I hope this helps.

And note, even after the factory reset the speaker will still show up in your account information here at Sonos.com until it is registered by the new owner.  

In addition to remaining registered to your system until it is formally adopted by the new owner, your controllers will show the unit as being offline for a few days. The controllers are assuming that you have temporarily powered down the unit while a construction project is underway. You can simply ignore this for a few days until each controller stops bothering you. If you have multiple controllers and multiple users this might annoy others. A controller reset or uninstall can work around this. If you decide to reset or uninstall each controller, be very careful not to startup a new system, you want to control an existing system. My own preference would be to ignore the ‘missing’ unit for a few days until a controller stops looking for it because this is less work for me.