These are custom XaaS items generally once you place these in vRA the entire lifecycle should be managed from vRA, where you would have a day 2 action that would delete and remove the object.
Now you could create a day 2 action and try and delete the object (there is a checkbox in the creation of the action which says is this destroying the object) but it may fail because the resource mapping that is in place if working correctly would likely fail because that resource is no longer in the plugin.
It might be easier to just go into the postgres database on the appliance and mark the object as deleted.
NuggetGTR Thanks for the input. For some reason the instances were imported and not deleted correctly through vRA and like you said when trying to terminate/destroy the object using a custom action it bombed. At any rate, I was able to work through manually deleting the instance in the vRA postgres DB which is unsupported so be cautious and take a backup prior to making any changes. Helpful tip for anyone with the same issue, the object will have to be deleted from the following locations/tables (see below) in the vRA postgres DB and in that order.