Similar Problem here.
I want to remove the calendar from the dashboard but still give the teachers the possibility of have calendars in the courses. So the general "hide" in the plugin/blocks settings is not a solution. And settings the block invisible does not hide it for other users.
Anyway, deleting the block in appearance/standard dashboard did delete it for all users. Users are not able to edit their dashboard, so i do not know if in that case they can still add it if they want.