Yep, I got an idea.
The UI elements in SAP HANA studio are not governed by any privilege management.
So you cannot prevent any user from _trying_ to open the admin editors.
However, on DB level, all admin actions are bound to system privileges, which are in turn usually grouped to roles.
It's pretty simple to setup a user who can do nothing successfully but opening the SQL editor window. Just start with the user who has nothing but public and add privileges you need.
If you look a bit around here on SCN you'll also find the nice set of template roles, that my colleague and co-author Richard Bremer had build. This should be a really good starting point!