Hi @SBSteve.

Welcome to the Sonos community and thanks for reaching out to us.I would like to help you out by providing you the following recommendations to check which would best fit your preference.

• If the Sonos Bridge is still showing on your Sonos account via logging in on our website as eligible for trade-up/upgrade, you may want to take advantage of it and use the program to get the Sonos Boost. 
• Feel free to call our sales team @+18006802345 option 4, they may have all the answers to your question about the upgrade program.
• If you have already grabbed the opportunity to get the Sonos Boost through the trade-up program, You can factory reset the Sonos Bridge and set it up for sale.
• Once the new owner registers the bridge on his Sonos account, that would be the only time that the Sonos Bridge would be removed from your Sonos account and appear on the new owner’s Sonos account.

I hope this helps.

Please let us know if you still have any further questions or concerns. Youa re always welcome here in the community.

Thanks,

You could also set up a temporary e-mail account and reregister the Bridge to that to clear your account.

If you check prices on ebay, $10-15  selling the Bridge isn’t gonna buy a pizza.