2016 e 400 stuck in park
just an FYI that you are in the wrong forum for your model as this is for 2017 and beyond E classes.
However, to answer your questions, if the E class is anything like my previous C class form the same era, the release is inside the leather boot that surrounds the shifter. If you use your fingers, and grasp the leather boot from either the right or left side border, you can remove the leather surround. The release is a white button on the inside


