Hi @raybeck ,
Not sure how exactly you installed Grafana on Ubuntu. But Uninstallation should be easy as well (if you use the Package manager apt-get or dpkg). For e.g. look at these links for references [1] and [2].
For the Windows O.S., I do not have such an environment but in Windows, you should simply use the Add/Remove Programs from the Windows Control Panel to do it.
I hope this helps.