I used to have two IP cameras (Foscam) that were hooked up through iVera. I’ve since gotten rid of the cameras, but cannot remove them from the iVera interface. When I go into the settings and click on the trash can it gives me two confirmation dialog boxes, then I get an error saying “Command Failed: Invalid Plugin”. How do I remove these two cameras?
Get the device ID and use the correct IP address for you vera. Enter the modified link below into you browser and it should remove them one by one.
http://<Vera_IP>:3480/data_request?id=device&action=delete&device=<device_ID>
The solution that Brientim provided should work. Also a little tip, a search would have found you the same solution. 
- Garrett
To help in searching, below are two examples of using google which would have returned the desired results.
site:micasaverde.com delete device
site:wiki.micasaverde.com delete device