If that restaurant DOESN'T serve breakfast, I recommend returning first thing in the morning when they won't be using that griddle. Otherwise...afterhours or R-E-A-L-L-Y early in the morning.
There is a make of a salamander out there (which I've worked on at a Cheesecake Factory) on which the top panel pops right off the salamander & the IR burner lifts right out of the top. However, that's NOT Vulcan's design. On the Vulcan, I THINK you disassemble from the front & everything comes out that way. I've never done one, so I'm not certain.
Your're right about cleaning it. Given it's location above the flattop, I've no doubt the IR burner's air inlet has clogged with greasy goo & you'll probably need to clean the orifice as well.