What does “exercise their desire out of them” mean?

Question

“I’m not sure whether they hibernate or not,” Hagrid told the shivering class in the windy pumpkin patch next lesson. “Thought we’d jus’ try an’ see if they fancied a kip … we’ll jus’ settle ‘em down in these boxes….”

There were now only ten skrewts left; apparently their desire to kill one another had not been exercised out of them.(Harry Potter 4 [US Version]: p.41) [Bold font is mine]

N.B.: Hagrid is a Care of Magical Creatures teacher. The skrewt is a dangerous magical creature.

I can’t understand 'exercise' in the above citation.

There seems to be three major definitions of ‘exercise’ (verb). 1. use power / right / quality; 2. do physical activity; 3. be anxious

I’m thinking No.1 is likely. I tried finding ‘be exercised out of’ on the Net.

As a May 1, just over 3 million 30 cent options had already been exercised out of the total of 744 million originally issued. [Bold font is mine]

But I can’t find any examples which have ‘desire’ as an object of the ‘exercise’. So, at one point, I thought it meant ‘physical exercise of skrewts couldn’t remove their desire out of their bodies by applying No.2 meaning.

Would you tell me the true meaning of “their desire to kill one another had not been exercised out of them”?

Answer 1

In the example used in your question, the skrewts had been exercised and were tired, so that Hagrid thought they might have a 'kip' (sleep), but their desire to kill each other was still present. The desire had not been exercised out of them by physical activity.

Answer 2

If one has been exercised to exhaustion, one has lost one's desire to "date," to kill, or to do anything constructive (or destructive), except to sleep. But the skrewts had not been "exercised" to this point.