The aux. fan shroud is held together by plastic push-pins/rivets which can be pryed off with a screwdriver.
If you can remove the vertical bar between the bumper and top horizontal bar, you be able to remove the aux. fan shroud. Otherwise, the proper procedure is remove radiator, remove condenser w/aux. fan assembly attached, then remove aux. fan shroud.
However, why do you think your overheating issue is due to the aux. fan shroud?
Personally, I would get a new radiator, clean out any debris in front of the A/C condenser and behind it, flush the system at least 10-times. And fill with 40% MB Anti-freeze and 60% distilled water, plus a bottle of RedLine Water Wetter. Also, replace any hoses over 5-years old, replace the thermostat & gasket if over 2-years old, and get a new radiator/overflow cap (essential to holding the correct pressure).
I have a 1995 M104 AMG in my 1988 W124 wagon, and in 110F Las Vegas heat the temps don't rise past 90-C.
1988 360TE AMG