Disconnect battery ground strap. You might be able to skip this step if you are confident and careful not to do amatuer arc welding of potentially hot wires in these harness plugs. I got by without doing this step your mileage and skill may vary.

Disconnect the two multi plugs from the alarm relay. These are fairly stubborn to disconnect. Requires a bit of pressure to remove.

I apologize for the fuzzy photo of the wiring harness but I was not able to get a clear shot. The second shot is a closeup of the relay after it is physically removed. I took that step because I don't want this thing annoying me while trying to drive the vehicle ever again.

The relay is attached to the kick panel with typical plastic movable core rivets. You can push the core out with any handy tool (I used a pocket knife blade). Mine had only one but hey this is a 31 year old car!!!

If you leave it attached to the kick plate you might want to tape over the harness ends somehow so they can't short against those exposed pins.

I understand later models of mercedes vehicles use the same relay but also have an additional relay in the dashboard that disables starting the engine. If you google you can probably find instructions for how to work around that "feature". I will not cover that here because I have no vehicle to provide photo context.