If you mean the block of the overview page, the page is made up of widgets. You can remove the profile posts widget.
If you mean the tab at the top, see the 
whats_new_wrapper template:
	
	
	
		Code:
	
	
		<xf:if is="$xf.visitor.canViewProfilePosts()">
   <a class="{$baseClass} {{ $pageSelected == 'new_profile_post' ? {$selectedClass} : '' }}" href="{{ link('whats-new/profile-posts') }}" rel="nofollow">{{ phrase('new_profile_posts') }}</a>
</xf:if>