Typically they'll let go immediately unless they panic.

Diluted vodka can make them let go, but it's toxic to them, so one has to be very careful with it and make sure they don't inhale it or swallow it. The other suggestion the thread had was was water; stick the relevant body part under warm water until he releases. (Have to be warm water so cold shock doesn't wind up an effect.)

He'd gotten a loop of my hair which made it possible to pull up the upper jaw; I detached him carefully with a finger. (Sliced the finger a little on the teeth, but much better than having an attached freaked-out snake.)