Rodrigo,
Never dealt with deleting pages before, so I had to do some research. Yes, you'll need to send a Page Access Token to delete the page, since FB needs to ensure the Page really wants to delete the tab. The code I sent above will send the App access token, which, now that I think about it, wouldn't be right.
So, you'll need to get the Page Access Token, and then try the following code:
$params['access_token'] = $pageAccessToken;
$removed = $jfbcLibrary->api($page_id."/tabs/".$app_id, null, true, "DELETE");
Note that the $callAsUser parameter was false, but is now true. That's to get around a forced setting in the function for the access token (another reason why we'll be changing the function in the next major release).
For information on how to get a Page Access Token, please see the page below:
developers.facebook.com/docs/reference/a.../#page_access_tokens
Page Access Tokens are, again, something I really haven't dealt much with, so hopefully you already have this or know how to get programmatically. Doesn't look too difficult, but not sure how you're trying to push this into JFBConnect.
Thanks,
Alex