i don't know much about this stuff, but if it's partially underground, a former shelter/ facility from the Cold War and people outside are observing it, then the best option might be to seek a secret passage/ tunnel. I imagine such buildings would have back entrances in case they were under attack, and if there were multiple ones and some of them were well-hidden, then the humans might not have found them. But the AI might have. Maybe the protagonist can ask it if there's such a thing, and after some convincing it'll show him/ give him a hint? Can't really think of anything else that might work. Of course if the humans get back in and read the AI's records before wiping them they'd find out, but by then he and whatever/ whomever he's smuggling out are probably long gone.
Good luck with your short story and I'd like to read it when it's finished: it sounds interesting!
Step 1: start an electrical fire.
Step 2: sneak out when the fire department gets there.
Okay, we'll see you all again in 2019, when this thread zombies again! 
windows like that? Well, if the cameras arnt against him, just sneak and open them... kill the camera system, something like that.
If there is a key, he gets it, or otherwise he picks it, or jars it open with a wedge/lift. Really, it sounds like sneak and mechanically moving something. Now if it was lasers and other things, it would work differently, but the proccess sounds straight forward.
as of the 2nd of Nov. has 6 weeks for a broken collar bone to heal and types 1 handed and slowly