Antonio,
Ryan has explained this perfectly.
For a more detailed explanation of methods for controlling page indexing, you could read this post on Restricting Robot Access for Improved SEO
It seems from your comments and questions about 301 redirects, that there is some confusion on how they work and why we use them.
A 301 redirect is an instruction to the server which is most commonly done by adding a .htaccess file (if you are using an Apache server).
The .htaccess file is read by the server when it receives a request to serve any page on the site. The server reads each rule in the file and checks to see if the rule matches the existing situation. When a rule matches, the server carries out the action required. If no rule matches, then the server proceeds to serve the reqested page.
So, in Ryan's first example above, there would be a line of code in the .htaccess file that basically says to the server IF the page requested is /apples, send the request to /granny-smith-apples using a 301 (Permanent) Redirect.
The intent of using a 301 Redirect is to achieve two things:
- To prevent loss of traffic and offer the visitor an alternative landing page.
- To send a signal to Search Engines that the old page should be removed from the index and replaced with the new page.
The 301 Redirect is referred to as Permanent for this reason. Once the 301 Redirect is recognized and acted upon by the search engine, the page will be permanently removed from the index.
In contrast, the request to remove a page via Google WMT is a "moment in time" option. The page can possibly be re-indexed because it is accessible to crawlers via an external link from another site (unless you use the noindex meta tag instead of robots.txt). Then you would need to resubmit a removal request.
I hope this makes clearer the reasons for my response - basically, the methods you have used are not "closing the door" on the issue, but leaving the possibility open for it to occur again.
Sha