To remove the unwanted plug-ins from the Available Plug-ins list:

  1. In a web browser, navigate to http://vcenter server name or IP/mob.

    Where vcenter server name or IP is the name of your vCenter Server or its IP address.

  2. Click Content.  

  3. Click ExtensionManager.  

  4. Select and copy the name of the plug-in you want to remove from the list of values under Properties. For a list of default plug-ins, see the Additional Information section of this article.  

  5. Click UnregisterExtension. A new window appears.  

  6. Paste the name of the plug-in and click Invoke Method. This removes the plug-in.  

  7. Close the window.  

  8. Refresh the Managed Object Type:ManagedObjectReference:ExtensionManager window to verify if the plug-in is removed successfully.

Refer:

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1025360