This is an inquiry about how to use the LT3466.
I would like to use only one of the two channels.
How should I handle the SW2, Vout2, FB2, and CTRL2 pins that are not used?
You may leave those converter #2 pins (SW2, VOUT2, FB2 and CTRL2) open.
However, I recommend to use LT3465 instead of LT3466 if you are driving 6 or less LEDs.
To be on the safe side, best to ground CTRL2 to make sure the converter is off. Other pins can be open.