add user document model

app/controllers/admin/user_documents_controller.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+module Admin
+  class UserDocumentsController < Admin::ApplicationController
+    def valid_action?(name, resource = resource_class)
+      ["destroy"].exclude?(name.to_s) && super
+    end
+  end
+end