Option #1.
Try to move the sealed (and unsealed) drone brood to the upper super, keeping them in the center, over the area where the bottom brood nest has brood. They'll be kept warm and complete development. When they emerge, they'll be out of the way and the queen should stay below and won't lay new drone eggs in the vacated drone-sized cells. Higher up, the bees will be able to fill the empty cells with honey.
Option #2
Scrape open the drone cells (thereby killing them). The bees will clean out the cells and you won't have an unneeded large population of drones for the hive to take care of. Often, a large number of drones in a hive at this time of year will inspire the family into swarming mode. By reducing the number of drones in the hive you will help reduce this liklihood (but it is not the only nor the best means for swarm prevention).
Option #3
From your description of the flowering situation, the bees should be in prime form for building new combs. You could remove the drone comb from the hive and replace it with frames of worker foundation for the bees to build. Keeping them busy building, combined with the added space in the hive, reduces crowding and also contributes (slightly) to reducing the swarming instinct. The foundation frames should be placed on the outer flanks of the brood nest. If the weather is really warm and the hive populous, you might even place a frame for building in the center of the brood nest, This move requires caution---if conditions aren't just right, it could lead to chilled brood on the outer sides of the brood nest.