code: func (api UsersAPI) DeleteUserRegistryEntry(w http.ResponseWriter, r *http.Request) {
  	username := mux.Vars(r)["username"]
  	key := mux.Vars(r)["key"]
  
  	mgr := registry.NewManager(r)
  	err := mgr.DeleteRegistryEntry(username, "", key)
  
  	if err != nil {
  		log.Error(err.Error())
  		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
  		return
  	}
  
  	w.WriteHeader(http.StatusNoContent)
  }
docs: // DeleteUserRegistryEntry is the handler for DELETE /users/{username}/registry/{key}
  // Removes a RegistryEntry from the user's registry