We are running SP2013 standard edition. We have scheduled full crawl at weekend and incremental crawl every 15 minutes. Recently we deleted a site collection. After a week when I check the crawl log a number of error is saying The object was not found. ( Error from SharePoint site: HttpStatusCode NotFound The request failed with HTTP status 404: Not Found
All of these error is about the deleted site collection.
Although I can click the error log and select remove the item from index
but I think it is not the proper way. May I know how can I make SharePoint forget the deleted site collection?