If you want to have all LEDs off, and only toggle LED 7 on and off, change the hex values from
// All LEDs on = FF FF
// LED 7 off = FF BF
// LED 7 on = FF FF
to
// All LEDs off = 00 00
// LED 7 on = 00 40
// LED 7 off = 00 00
It's actually LED 2, not 7, depending from which direction you look at the LEDs on the board.
I've got all the LEDs fired up to determine how long they'll last, but others may just want turn individual LEDs on and off, while leaving the rest off.
Here's an online binary to hex converter script I stumbled across, it's handy for visualizing if your not a binary to hex guru.