I'm assuming that the black piece is the dash console cover that fits over the HVAC controls and HU opening. When ever I have had to remove those I have had to look for screws which can be mounted under the dash, in plain site, or in other hidden areas. Look very closely for any screws. depending on the vehicle, sometimes you may have to pop out the air vents to reveal the screws. Some of the console covers just pop off with a prying tool. It all depends on the make and model of your vehicle. I know there is a web site that explains HU removal but I can't remember it. Try using a search engine to find it.