So, you installed Fedora Workstation on your server and ended up not using the desktop environment after all and want to convert to Fedora Server without doing a re-installation? It's very easy to do:
- Boot to console:
systemctl set-default multi-user.target
- Change identity:
dnf swap fedora-release-identity-workstation.noarch fedora-release-identity-server.noarch
It might take an update of the kernel before the server calls itself "Fedora Server".
While it is possible to completely remove a desktop environment, things could break:
sudo dnf remove "@Basic Desktop"