removing rear fastener on sns profil binding

Hi - I'm replacing a profil binding with a new pilot binding. I've
removed all the old binding except the heel plate which is attached by
a small yellow plug in at the rear of the heel plate. All adhesive has
been pried free so the heel plate is rotating about this plug.

The profil binding is a grey model about 2 years old. The little
yellow plastic plug has a slight flat head screw slot in the top but
I'm pretty sure this is not for unscrewing.

My recollection is that this is a little expander plastic plug that I
pushed down into a hole in the ski but I really can't remember.

How can I remove it? Pry the heel plate off until it breaks? Drill it
out? Is this a replaceable part I can find if I want to re-use the
binding?

Thanks for your help!!

Regards
Chris