Kid quits team during game.

[BillyMac]

9-3-3: A player shall not leave the court for an unauthorized reason.

Here's a technical foul reference that won't work:

10-3-2: A player shall not: Purposely and/or deceitfully delay returning after legally being out of bounds.

This will work:

10-3-5: A player shall not: Delay the game by acts such as:
a. Preventing the ball from being made live promptly or from being put inplay.
c. The free thrower fails to be in the free-throw semicircle when the official is ready to administer the free throw unless the resumption-of-play procedure is in effect following a time-out or intermission.

So will this:

10-3-6: A player shall not:
h. Removing the jersey and/or pants/skirt within the visual confines of the playing area.
i. Leave the playing court for an unauthorized reason to demonstrate resentment, disgust or intimidation.

Pick your poison.