Change black color from mix to 0c 0m 0y 100k

Hi all,

a requirement of my printer is that black color should be pure 0c 0m 0y 100k, not any other 4 color mix. Using Acrobat XI Pro, is there a way to change this in an existing PDF? I found the color conversion dialog in the printing tools but I could not find out how to perform this task.

I would be very thankful for a short hint!

Robert

Edit: There is an option "enable CMYK grey scale to black". The text on the German UI is not clear to me - is that the option I need to use?