On My year and model that is where the Safety Belt Buzzer Goes.

To remove it you need to slide something Flat on each side through those slots of the Switch to depress the sort of Plastic Hooks on each side and also push in the Switch Button.
It looks like the ideal thing would be the flat sections on 2 Bobby Pins with the rounded Plastic Ends removed from the Bobby Pins.
You man need to thin the width of the Bobby Pins.

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84 300D, 82 Volvo 244Gl Diesel