If Zach wanted, he could have entered the middle hell quietly and stealthily killed the guards, but he didn't. If he did, that would have taken him hours to get rid of all the guards from the city. Not to mention, he would have gained no intel on the inner hell.
Even if he had managed to get some information from one of the guards, that would never have been enough. Therefore, Zach started the revolution and lured all the guards to one place where he could interrogate them and then execute them accordingly.
It was all part of Zach's plan from the start. And now that he had got what he wanted, he had no need of the guards.
The same guards who had closed the windows were now opening them so they could escape. But whoever attempted to move ended up getting sliced into pieces.
"Don't fear!" the leader of the guards said. "He is the only one! And we are in the hundreds! Look around you and find him! He is undeniably in this chamber! Don't let him escape."
