It's on the console, at the base of the throttle handle, on the left side of it, and slightly behind it.
I disagree with whoever said it's real obvious in VR. It wasn't to me. It's a tiny black handle, on a black panel, hidden behind the large black throttle handle. I was looking right at it, multiple times, and never saw it. It's practically invisible.
If you move your cursor around the base of the throttle you'll see it turn into the green up/down arrows at some point. That's the parking brake... even though you can't really see it.