delete polictDef in ApiMan via GUI

Question

I have added Policy Definition wrongly instead adding it as custom Plugin.

  "id": "test-policy",
  "policyImpl": "plugin:${project.groupId}:${project.artifactId}:${project.version}:${project.packaging}/io.apiman.plugins.test.TestPolicy",
  "name": "Test Policy Plugin",
  "description": "Test policy plugin",
  "icon": "lock",
  "templates": [],
  "formType": "JsonSchema",
  "form": "schemas/test-policyDef.schema",
  "deleted": false
}

Now if I try to add the plugin, it complains that the plugin with name already exist. There is only option to update policy and if i try to set "deleted": true. It does not update at all as I can see the configuration remains unchanged.

How can I delete this policy definition and install it as plugin. I think I can change to new "id" and add it as plugin. Is it possible ? But is there no way to delete the policy directly ?

EDIT : I can add it as plugin with new "id" as it the primary key in ES registry. But still cannot find a way to delete it. Where are the policydefs stored in the system? Can we delete using ES query?