When you set-up a proper website management in large organisations you’ll end up in having two main groups: designers and content editors.
Normally you want the designers to be a more powerful content editors; with added functionality like selecting which components you can use for contributing the pages.
In order to remove the “design icon” from the Sidekick for a specific group/user you simply have to act on ACL and remove everything but Read permissions on /etc/designs.
Read Modify Create Delete R/ACL E/ACL Repl. /etc/designs V x x x x x x