how to uninstall macport with OS conflict ?

[db]

On 19 May 2017, at 00:00, Clemens Lang <cal at macports.org> wrote:
> Run the MacPorts installer for your new OS (yes, I know it's counter-intuitive), then follow the uninstall instructions. It should only take a couple of minutes if you use the installer and allow for clean removal even if you had ports installed that install files outside of /opt/local.

I still haven't had this problem, but does running the installer for the current OS version uninstall the previous base and ports _and_ reinstall the requested ports? If not, as I presume, shouldn't it be an option?