Terminating the chase is generally the OIC's responsibility, that will most likely vary from area to area, but in general, that is how they get terminated, on occasion, the officer(s) in the pursuit will self terminate if it gets too dangerous.
Lights and siren do not give you an automatic "green light" to drive dangerous, sometimes people in surrounding cars are distracted (hard to believe,huh?), don't see the cruiser, hear the sirens etc..., or maybe it was just an unfortunate occurrence that resulted in a traffic crash.
You do need to consider some things, if the police are chasing a vehicle, maybe it was used in a robbery, murder, shooting, kidnapping, if any of those things involved you or your family, would you want them to pursue? Or maybe just break it off because someone could get hurt? Same thing with responding to a suspicious person(s), breaking and entering, robbery in progress. The ones that are so "anti-police", I would urge you to go on a "ride along" to see what some of these guys face every day of the week, it will open your eyes.
We've all gotten traffic tickets for stuff we have done, sometimes for stuff we haven't done (me included), I don't harbor any ill will for the police for it, I am sure I deserved what I got as I have gotten away with plenty of infractions. Just sayin'