Hello,

Unfortunately, this part of UI cannot be customized in Kentico CMS, only it's use can be disabled by setting role permissions. The only option how to remove these buttons is to edit the code and add custom checks in code behind.

You can find documentation about how to find out which part to edit in which file here:

http://devnet.kentico.com/Knowledge-Base/API-and-Internals/How-to-find-the-location-of-the-code-for-a-page-us.aspx

Best regards,
Josef Dvorak