I would recommend also unsetting block name "wishlist.sharing" as without doing so the wishlist can still be reached by url http://www.yourmagentowebsite.com/wishlist/index/share/1234/ and could be exploited by spammers (1234 is wishlist ID).

Comment out the following in wishlist.xml like so:

<!--<block type="wishlist/customer_sharing" name="wishlist.sharing" template="wishlist/sharing.phtml" /> -->

or add this in your local.xml:

<wishlist_index_share translate="label">
    <reference name="my.account.wrapper">
        <action method="unsetChild"><name>wishlist.sharing</name></action>
    </reference>   
</wishlist_index_share>

I would recommend also unsetting block name "wishlist.sharing" as without doing so the wishlist can still be reached by url http://www.yourmagentowebsite.com/wishlist/index/share/wishlist_id/1234/ and could be exploited by spammers (1234 is wishlist ID).

Comment out the following in wishlist.xml like so:

<!--<block type="wishlist/customer_sharing" name="wishlist.sharing" template="wishlist/sharing.phtml" /> -->

or add this in your local.xml:

<wishlist_index_share translate="label">
    <reference name="my.account.wrapper">
        <action method="unsetChild"><name>wishlist.sharing</name></action>
    </reference>   
</wishlist_index_share>