Editing Media drop down list

I have added some extra types of binding under the Books section of the Media drop down list. Some additions need deleting. How do I do it?

I don't think there's an option to delete

>2 SandraArdnas: Is an addition editable?

Sadly no. I have several additions which I would like to edit (e.g. misspellings) or delete where I've added a better alternative.