Yeah. It's a bit complicated, but do the following:
- Hit the 'Home' Button
- Press "Wii Remote Settings" down at the bottom of the screen
- Press the "Reconnect" button
- Hold down 1 and 2 on the controller you wish to be ON
- After it connects (you can tell by there being a battery that is 'lit' at the bottom of the screen), hit 'B' to exit out
- Press "Close Wii Remote Settings"
- Hit the 'Home' button or press "Close" at the top of the screen
That should do it! Just make sure you only reconnect the one you want to be ON. The other should turn off automatically
Hope this helps!