Well when you refresh the page, it should show your cookie in there (alongside that one you showed us) when you visit a page after you have deleted it, it should not be there.
To focus in on this issue, create 3 different pages, 1,2,3.
1 sets the cookie
2 reads the cookie
3 deletes the cookie
All with var_dump() at the top of the page, also depending on your browser install some "developer tools" so you can see the content of any given cookie at any time.
Once you get it it is easy to work out what you are doing wrong. (Having said that, be warned that localhost is not the same host as 127.0.0.1 and I have run into issues with IE not reading cookies set on localhost, 'twas years ago though)