In SharePoint 2010, Removed was Removed!
In SharePoint 2010 there's a search feature called "Search Result Removal" that made an item immediately disappear from user's search results. All you had to do was enter the URL to the problem item and click Remove Now. SharePoint then remove the item from the index and wrote a Crawl Rule to make sure the content was ignored by the crawler in all future searches.
The 2010 request to remove:
The auto-created Crawl Rule:
SharePoint 2010 had a interesting bug here. Uppercase letters in the URL would cause the the removal request to be ignored!
In SharePoint 2013 and Office 365, Removed is Just a Temporary Thing! Maybe only a few seconds!
We don't have Crawl Rules in SharePoint 2013 and Office 365. When you request the removal of an item or a URL from the search index, it just deletes it from the index. But… on the next crawl it adds it back! That next crawl could be an hour away, or only seconds, depending on your crawl schedules and the luck of your timing.
Nowhere can I find any documentation that says this!
The screen for removal requests is similar to what we had with 2010, but with no mention about Crawl Rules.
Removal Straight from the Crawl Logs
Both versions let you browse the crawl logs, find a problem item, click the dropdown on the item and click Remove the Item From The Index. In the Crawl Logs you can remove one item at a time while the Removal pages will let you exclude and entire path.
In 2013 we are just told that the item will be removed. In 2010 we are also told that a crawl rule will be created.
Remove URLs from search results (SharePoint Server 2010
Delete items from the search index or from search results in SharePoint Server 2013