To remove an item, select 'Manage your Menu' from the Admin Console and then select 'Manage Menu Items'.
Find the item you want to remove in the table below the input form, click on the 'Action' button to the right of the menu and select 'Edit'.
The item will be copied into the input fields of the form at the top of the page. Scroll down to 'Currently Available' and select 'No'. Click on 'Update This Item'. The item is now no longer visible on the menu.
To permanently delete an item, go to the same table as described above and select 'Delete' after clicking on the 'Action' button to the right of the item in the table.