What tool or special bit do I need to remove this (will add the name later when I know it :-) )

I do not know the name of the hardware that I need to remove, please see the picture below. The brass like colored piece is stuck there really well. I have tried with a screwdriver, I pushed with a hammer…no results.

I need to remove it and to somehow recover the functionality of this casement window operator which stopped functioning because this thing was loose and it was coming out. I guess the thread is gone

Edit: it seems that this is what I need (Universal Adjustable Angle Grinder Pin Wrench)

Edit2: they are quite expensive, here isone that you can make yourself, provided that you have the right size for the rod