Maybe you can reinstall the server and run a /Mode:RecoverServer switch, after the installation you can try to uninstall it the correct way.
This is for 2019, but steps on that should still be same:
If that fails, try these steps:
If its an old dead server then remove it from AD using ADSIEdit and perform the uninstall again :)
I only have one - if you have a second entry for this server delete it from here;