Perhaps not the place to be discussing coding but I think the issue is related to the domain that set the cookie not the technology that set the cookie. The browser doesn't know how the cookie was set, or at least that information is not stored in the cookie.
For Google analytics cookies the js I quoted is OK as GA cookies are set by js. You could have a link to a php script in noscript code if you want belt and braces.
Like you I don't think it is acceptable to tell users that if they want to delete cookies they should go to a page that explains how to do it manually in their particular browser.