When a page is no longer needed, it's time for it to fade into the archives. Unless there's some important reason to destroy the content, it should be kept, for history. Now, if the item is on the front page teaser view, it will eventually fall off the bottom of the page, and that might be enough to relegate the page to history. If not, either because it's in one of the features of the front page, or because you need it to be gone right away, then you need to take more action.

So, edit the item.

If the page is connected to either of the feature panels, or the dynamic display block, remove that connection by deleting the reference in the "Display Block/Features Selector" box.

Under "Comment settings", select "Disabled".

Under "Publishing Options", leave "Published" checked, and be sure "Promote to front page" is unchecked.

That's all there is to it. The search engines, and the search feature on the site itself, will remember where the page is, and will still  be able to find it. But