What list are you trying to remove them from?  If it is the list of rooms in the app, just turn them off. The rooms listing will update after a few days (to keep speakers from disappearing just because you turn them off for a period of time).  If you mean your list of speakers in your account information at Sonos.com, they won’t disappear from that until someone else registers them. 

Removing 1’s from the list, meaning removing from the system. 

Are your Sonos Ones currently your surround speakers? If so, on the app you need to go into the settings for the room with the soundbar, then go to Remove Surrounds. Then you should be able to add your Era 300s as surrounds.

You should also be able to remove the Ones too. 

Yes the Sonos Ones are currently my surround speaker. But the remove function is not working.