Deactivating Mail Merge on List Items (Marketing Lists) button

Hi, 

Is it possible to somehow regulate the rights to the button: Mail Merge on List items (under marketing lists)? 

We are using ClickDimensions for sending out emails, but recently found out that there are some subsidiaries that are sending their emails out via using this button. Therefore we would like to either regulate the rights to this button or remove the possibility completely. 

How can that be done?