How can i completely delete a page and then re use the content without getting flagged for copied content?
You mean get de-indexed? And then reinvent the site? Or just remove a page on a site and use the same text on another one?
depending on how fast your site gets indexed, it will be a deleted/non-indexed page after you delete it so you can place all the info on another page without a problem
Some of the pages I deleted returned a 404 Page not found in the Webmaster tools and were indexed for a while in the google cache. It might be better to put a <meta="Robots" content="noindex"> tag on the page you want removed from the index. But I think doing a 301 redirect to the new page will be better as it tells google that the page has moved permanantly and will also take the SERPs and PR over to the new page.
I also think that would work best regardless of whether you're trying to de-index or just move the content to a new page. Might as well take advantage of existing indexing.
Qazu and sweetfunny are right. Just do a 301 redirect from the old page to the new one. It's like moving from one house to another in a way. Unless you tell everyone what your new address is, all your mail will still go to the old place (though when it comes to junk mail, I really wouldn't mind! ).
if you want to change all of the web site content, just delete and build a new one . search engines bot will visit your site and reindex your new site
If it is just that single page 301 it through the htaccess file to either a new site that you are placing that content on or if it is staying within the same site write new content on the same subject for that page and link it to the new page you are creating with the old content. This way if it stays within the same site you will be able to keep the new url out of the supp index and if this old url has PR then you can pass PR and also create more content for that same key phrase you are targeting.