http://codex.wordpress.org/Template_Tags/wp_list_pages#Exclude_Pages_from_List

This covers the basics of how to exclude pages from your navbar listings, but there’s only one problem (and at first I was freaking out over this): they indicate to exclude by page ID, but the newer versions of WordPress don’t use a page ID, SO, here is what you do:

1) Go to ‘Pages > Edit’
2) Mouseover the page you will be wanting to exclude from your list, and see the URL that appears (for example: http://www.kevinpajak.com/blog/wp-admin/page.php?action=edit&post=2). You notice that you will actually see the number listed as a post!
3) Grab this number for each page you need to exclude, and plop it into this code in your header/sidebar/navbar page code:

For example:
<?php wp_list_pages(‘exclude=16,18,20,22′); ?>

Voila! You should be all set (Oh, and if your wp_list_pages function happens to have additional code, you will need to make sure you include the ampersand character with it (&).

Ex:
<?php wp_list_pages(‘title_li=&exclude=96,98,100,102,104′); ?>

Last of all, there is also a plugin you might want to try, called ‘Exclude Pages’ that should take care of this for you automatically if you prefer. I haven’t tried it yet, but definitely worth a look .

Have fun WordPressers, good luck, and please feel free to share your feedback anytime! .

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PS: To exclude categories from your navigation listings, follow the same procedure:

1) Take a look at your overall category list (‘Edit > Categories’),
2) This time find the CAT ID (Ex: http://www.kevinpajak.com/blog/wp-admin/categories.php?action=edit&cat_ID=3)
3) Note that number(s) and enter them in the line of code that reads, for example:
<?php wp_list_categories(‘exclude=6,8,21′); ?>