As I stated above, you are not logging into a specific server. Please forget this concept, it won’t do you any good.
Here: https://app.plex.tv/desktop/#!/settings/devices/pms
(only remove decommissioned servers, not the one[s] you are currently using)
Here is how to claim servers on Windows now: New Claiming Requirement for Windows
If you are trying to re-claim a server, which has been claimed before already, you might have to perform this procedure beforehand: You need to reclaim your server, but don't dare to touch the Windows Registry
