Add to Calendar for Admin Only

[ThinhDinh]

As far as I aware that is not possible. You can not set a visibility condition with that add button, nor limit the ability to add based on a condition.

Jeff also wrote about that here.

Conditional Add permission

No, there currently isn’t a way to conditionally show the add button, but if you wanted, you could set your tab to the details style layout and conditionally show a form button that would function as your add with an inline list of the data on the screen.