how do i remove my timing case cover in my holden rodeo 2.8ltr td

I don't have any reference information for this vehicle. None of my resources list a 1990 Isuzu (or Holden) Rodeo.
On most engines, you need to drain the cooling system. Next remove the accessory drive belts. The water pump has the fan mounted on it. Remove it. The timing chain cover is behind the water pump.