Thunderbird continues to prompt to sign in to deleted account

I deleted from Thunderbird an old University account that had been deactivated, but Thunderbird still prompts for those credentials. I copied messages from that inbox to a local folder and then deleted the account. Then I deleted a calendar connection for that account, and finally the outgoing server for that account. I can't think of anything else, but it continues to prompt to enter credentials for that e-mail address. When I deleted the account there were two options. One was something like "delete everything" and the other was akin to "leave some stuff". I don't remember the details but I chose the latter figuring it might goof up the local folder copy otherwise. The school must have used google, since the prompt is coming from googleapis.com. Any ideas on how it still knows about that old account? Thanks!