Be aware of your surroundings, locking on and moving to dodge attacks without thinking about the limited space will see you falling to an early demise. Your best bet is to sprint down and past them, then turn back and fight. You can try and perform a drop strike on one of the guards, but if you miss, it could turn very ugly. Be careful as there are two hollow soldiers on this platform. You have to drop down once more to the second ledge to the left.
You can make your way down here by walking to the edge of the entrance and dropping down onto the planks of wood. Head back outside and below you is a grassy area filled with hollow soldiers.