During the initial steps of the uninstall wizard, I get the prompt "Confluence failed to shutdown. Please kill the process manually before processing." However, I have confirmed that the Confluence service is stopped, the Tomcat
process is no longer running.

I had installed Confluence yesterday in order to demo it out, as we're probably going to purchase it. However after installing, the service started up, however the web page was not accessible. I could see Tomcat started, and it was attempting to load the initial page but then failed. Then I attempted to uninstall, as I wanted to install using the Run As Adminstrator option on Windows 2008, but then I ran into this issue.