If you rather not touch the Registry directly, I have prepared this:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Plex, Inc.\Plex Media Server]
"PlexOnlineHome"=-
"PlexOnlineMail"=-
"PlexOnlineToken"=-
"PlexOnlineUsername"=-
Copy the above into your clipboard.
Open the notepad.exe
Paste the text in.
Save the document.
Rename the file, change the filename extension from .txt to .reg
Double-click this .reg file, confirm the prompt.
(do this while Plex Server is not running in your task tray.)
