rake routes
is your friend here. It'll spit out the list of your generated routes - particularly useful if you have a bunch of nested or custom routes.
the paths will be
admin_pages_path #(with GET) routes to :controller => 'admin/pages', :action => 'index'
admin_pages_path #(with POST) routes to :controller => 'admin/pages', :action => 'create'
new_admin_page_path #(with GET) routes to :controller => 'admin/pages', :action => 'new'
edit_admin_page_path(:id) #(with GET) routes to :controller => 'admin/pages', :action => 'edit'
admin_page_path(:id) #(with GET) routes to :controller => 'admin/pages', :action => 'show'
admin_page_path(:id) #(with PUT) routes to :controller => 'admin/pages', :action => 'update'
admin_page_path(:id) #(with DELETE) routes to :controller => 'admin/pages', :action => 'delete'
Your link_to for delete should therefore be:
<%= link_to("delete page", admin_page_path(@page), :confirm => "sure you want to delete this page?", :method => :delete) %>
Note that Rails will work its magic calling to_param
on @page, so that you don't have to specify @page.id - useful for an example like this as you often want to use permalinks for 'pages'.