Earlier quoted context omitted.
As I understand it is mostly handled by the chipset firmware these days, and no options are available to disable it because it is a legal requirement. But even if you were able to disable the functionality, the carriers towers can triangulate you.
It's revolting that we've allowed functionality to betray its owner to be legally mandated into "our" devices. It's no surprise that they keep this so very discreet. Edit: I am specifically referring to the e911 ability to without owner interaction or knowledge send GPS coordinates, not to network-side triangulation, or even to sending GPS coordinates when the owner initiates a 911 call.
(As others have noted there may be some confusion here between GPS data and cell tower triangulation.)