Deleted account still tries to authenticate

I deleted a Google email mailbox that I no longer use. However, everytime I start up Thunderbird it still tries to authenticate and login to that mailbox. I removed the connection from my outbound mail servers but do not know where else to look. The connection is to a Google Mail box and it automatically pops up a browser window with a Gmail login prompt each time I start Thunderbird. Also, all my other connections to my other (non-Google) mailboxes are stuck and will not send and receive messages. Any advice would be helpful! Thank you!