Dodge 2016 Challenger Owner's Manual page 16

14 THINGS TO KNOW BEFORE STARTING YOUR VEHICLE
To remove the emergency key, slide the mechanical latch
on the back of the Key Fob sideways with your thumb
and then pull the key out with your other hand.
Mechanical Latch On The Back Of The Key Fob
Emergency Key Removal
NOTE: You can insert the double-sided emergency key
into the lock cylinders with either side up.