For future reference, look up
this table for device names, because Amazon's marketing names are mindbogglingly unhelpful
.
If you're already tweaked the store button, I'd imagine masking the KUAL Kindlet involves playing with Collections in one way or another... No idea how that works, and if you even can do it directly on FW 5.6.5. (You may have inherited that from something that could be done on earlier FW).