remove approvers for a shared calendar only

Hello,

I have 2 board room calendars that are shared on my Teamsite but I want to edit the approvers for those 2 calendars only.  

I went into the calendar and then to Calendar > List Permissions > approvers and removed the Administrator user but that seemed to have removed it from all other lists as well.  I only want to remove it for these 2 calendars.

How can I accomplish this?

Thanks,