I'm new to installing server frameworks but I don't see anywhere in the documentation of http://www.tornadoweb.org/ of how to uninstall this. Do I just remove the build folder?
You can just remove tornado's source code folder, which is probably located in ../python2.x/dist-packages. Keep in mind that Tornado is pure python.
Try uninstalling using python package manager pip.
First find the version of tornado installed
pip list | grep tornado
and then uninstall it,
pip uninstall tornado==<version-number>