I tried to do the same for my Hyundai Elantra 1992, as the engine is damage & nobody wants to buy it even for QAR 1500.

I removed the plate number & went to Murur at Madina Khalifa to cancel it. After completing the form with the typist in the back side of Murur office (cost QR10), I went to the administration area (the room with long bar & lot of queue numbering), the recepsionist there inform me to go to inspection section on the other building (outside of the Murur office, on the direction to the health center) to get the stamp on the form.

On the inspection area, the officer ther asked me to brought the car for inspection (I think they want to ensure there is no legal violation/accident on the car). But till now, I still have no time to bring it by carrier truck, have no time yet.

Hope it helps.