Moving desks, changing teams, or handing a speaker to someone else? Clear its old pairing first, then set it up on the new Sonos account.
If you still have access to the account the speaker is currently on, open the Sonos app, go to Settings → System, select the speaker, and choose Remove. This is a courtesy step, not a requirement: the factory reset in step 2 forces the speaker off any account regardless, which matters if you've lost access to the old one (a rep who left, for example).
Unplug the speaker, wait about 5 seconds, then hold down the Join button (the small button on the back or base; check your model) while plugging the power back in. Keep holding until the light on top starts flashing orange and white, then let go. On battery speakers (Move, Roam), hold the power button for around 10 seconds instead until the light flashes. There's no separate Join button.
A successful reset ends with the light cycling green, then settling to a solid state ready for setup. If it never starts flashing orange and white, unplug it and try again. The button usually needs to be held through the full repower, not just before it.
A freshly reset speaker behaves like a brand-new one. Follow the connect a speaker guide to add it to the new Sonos account and give it a room name.
Once it's added to the new account, head back into MeloDeal's team settings and re-select it under the new Sonos connection. The setup guide walks through that step if it's been a while.