You would uninstall PMS using the QTS App Center.
You would then remove the entire directory structure that the qkpg created.
Where is the Plex install directory?
When I log in via SSH as admin and use the command
[~] # getcfg -f /etc/config/qpkg.conf PlexMediaServer Install_path
/share/CACHEDEV1_DATA/.qpkg/PlexMediaServer
I can see that I need to rm -rf /share/CACHEDEV1_DATA/.qpkg/PlexMediaServer
but I’d rather not try it now to test that I didn’t forget a trailing slash or something 
