Remove Directory from Url name

I have a site done in asp. The url for an item is www.sitename.com/item/"itemname" and the url for the category page is  www.sitename.com/category/"itemname" 

I want to remove the directory item from the first one and just have it be www.sitename.com/itemname/ and same for the category. What would I do? 

Wanted to add that the site is done is asp and the pages are dynamic.