If, for whatever reason, you need to remove an entry from the magento admin menu, you have two simple options. Remove it using css, or alternatively, drop the following into a custom module's adminhtml.xml.
This overrides the core code pool's adminhtml definition, and puts a dependency on a non-existent module. Effectively, this disabled the menu item because it no longer meets the defined dependency requirements.
As always with any magento configuration / module changes, you may need to clear caches for this to take effect.