In BitBucket, my clone URL uses my new username. In Sourcetree, I'm logged in as my new user name, with the new username as the default. However, the older user name still exist as a 'resting' password.
When I use the BitBucket clone URL, it says "This is not a valid source path/URL". More details: "Invalid username or password. If you log in via a third party service you must ensure you have an account password set in your account profile."
I haven't been able to do a hard uninstall of Sourcetree. It still retains my old username, which I believe is causing this issue.