Answer
You can use a combination of the Visibility Plugin with the Style macro to show the button only to space administrators.
to hide the Edit button
to hide Edit Contents button
Since we introduced the in-page editor, the ID of Edit Contents button has been changed from editScaffoldLink to edit-scaffold-link.
You may also enable the HTML Macro, however, be aware that Enabling these macros can make your Confluence site vulnerable to cross-site scripting attacks.