Server "currently unavailable" - but I not really?

What now!?

I tried a fresh server on a backup computer - and this came up functional.
So - I figured I could remove the current (faulty) server and start from scratch.

Easier said than done!!

I remove the old server, both from my computer (uninstall and delete folder), windows registry and in the plex settings (remove), but when I install plex server again, an identical server popus up again, same library and name. It is impossible to start from scratch for me.

What am I doing wrong? Why cant I kill this zombie server?