I agree, and ideally the whole toolbar should be editable with different options based on different roles (such as Admins see one thing, users see something else)
It seems that the mentioned buttons are OOB Inbuild buttons and hence cannot be removed using Ribbon Workbench. This seems to be a restriction at this moment, hence posted the idea to see if this gets picked up and implemented in future releases.
We couldn't find a way to hide these menu via Ribbon workbench. I could be wrong.
Moreover Ribbon workbench changes apply to all security roles and above option can be restricted to particular security role which we found to be added advantage.
I haven't tried Ribbon workbench deployed with xrmtoolbox. Kindly let us know if it was possible to hide these options via ribbon workbench deployed within xrmtoolbox.