I'm sorry for the late reply. I know its been awhile but I wanted to ensure and see how I could help.
Your Nest thermostats are still associated with your account even though you removed them from the Nest app. To reset it, please follow these steps:
Let us know if it works.
Chiming in to see if you still need assistance with this. Hope the previous post helped. Let us know if you have additional questions, otherwise we’ll be locking the thread.
Due to inactivity, I'll go ahead and lock this thread in 24 hours. Feel free to start a new thread if you need assistance with your Nest devices and we'd be glad to assist you further.