Thanks for posting and apologies for the late response. Here are some steps below that you can try.
You can check out this link for more additional steps.
Keep me posted.
Thanks for the help Mlabrador.
@Henrik1, Nickp104, if the old devices can't be deleted from the Home app, that means the devices are not available anymore, right? If you can remember, what Nest devices do you have? Have you tried going to your account settings to remove the devices there? If not, then open this link to remove/unlink your devices from your account and tell me how it goes.
Thanks for the response. Check the steps below on how to clear the cache and data of the Home app.
Hope this helps.