The only moves it will know (besides harden) are the ones it learns while being a caterpie (string shot, tackle and bug bite).
It doesn't delete these moves automatically when it evolves into a Metapod.
As for the other point of view, wild Metapod must be considered to of somehow skipped their former stage of evolution or was simply never a Caterpie: it was born as a Metapod. Out of my thoughts of insanity I won't go any further into Pokemon reproduction as it doesn't 'float my boat' so to speak.