You can edit user-defined, reusable, and non-reusable metadata extensions for repository objects using the Designer. To edit a metadata extension, you edit the repository object, and then make changes to the Metadata Extension tab.

What you can edit depends on whether the metadata extension is reusable or non-reusable. You can promote a non-reusable metadata extension to reusable, but you cannot change a reusable metadata extension to non-reusable.