Well, poor design, but this is my solution.
Problem: Back Oven Grates are NOT removal making cleaning difficult. Kitchen is under construction and dust/particles are trapped.
1. Remove the Black Spacer (if installed).
2. Unscrew each of the vent grates
3. File down to pointy parts that line up
with the holes on the top of the cooktop
4. Return both grates to the back of your cooktop.