added `removeForResource` method

app/services/content-vote.js

@@ -90,6 +90,11 @@ class ContentVoteService extends SiteService {
     const updatedResource = await ResourceModel.findById(resource._id).select('resourceStats');
     return { message, resourceStats: updatedResource.resourceStats };
   }
+
+  async removeForResource (resource) {
+    this.log.info('removing all votes for resource', { resourceId: resource._id });
+    await ContentVote.deleteMany({ resource: resource._id });
+  }
 }
 
 module.exports = {