changing file names

I have changed some file names on my site to be more search engine friendly. For example: say www.domain.com/petfood to www.domain.com/pet-food. I have changed my sitemap to reflect the changes. Do I need to remove the old URL's from google using google tool or should i just delete them from my server, or not do anything at all? Some of the older pagers are indexed with google. I want to do this in a way that I don't get penalized or lose traffic. Thanks

 

Dont remove anything the urls will be automatically removed from google index

 

You could put a redirect on those old pages to the new pages.

 

once google recaches the new pages it will remove the old ones

 

The nice thing about keeping old pages is that google likes old pages.