The advantage of drone delivery is that it can efficiently use the vertical space in the air, allowing multiple operations at different flight levels. However, flight level and delivery efficiency come at a tradeoff, especially in a metropolitan area with many skyscrapers; placing drones higher requires more time, but the higher they are, the less detour they make due to the smaller number of buildings at higher altitudes, resulting reduced time in routing. This study integrates the problem by dividing the heights and identifying buildings that could possibly be an obstacle. We propose a novel vehicle routing problem for multi-flight level drone delivery to minimize delivery completed time.