I had loads of plugins in the New list of the plugin manager. I deleted them from the folder, and they still showed in New. Disabling took them to the now cluttered Disabled list. The Clear button does nothing.
The Plug-in Manager has no way at the moment of removing New or Disabled plugins from its list. I’m inclined to think that when launching, the Plug-in Manager should remove plugins from the list if it does not see the plugin in the listed path.
The only way you can currently remove the redundant entries is to exit Audacity then delete the file
“Documents and Settings<your user name>\Application Data\Audacity\pluginregistry.cfg”.
If you cannot see the “Application Data” folder, type
%APPDATA%
into the Explorer address bar then press ENTER on your keyboard. Then you will need to re-enable the plugins you want to use in Plug-ins Manager.