By putting the wiki word "DeleteMe" on a page you are signalling to an administrator of the site that you think the page needs to be deleted. The most common reason that you would want to delete a wiki page is if someone created the page for no real purpose (like a test page).
Sometimes people think a page should be deleted when the entire contents have been moved to a new page do to refactoring. However in general you are better to leave a redirect on the old page which points to the new page incase there are any stale links (either on the internet or within the wiki). You can make a page redirect by putting this on the very first line of the page:
#redirect NewWikiPage
Note that this is also the same process that any non-administrator can use to rename a page. Simple copy the raw contents of the old page to the new page and then leave a redirect at the old page.
List of pages which are currently requested to be deleted: