I think you should leave it... I think it is good to see the development of artists. That is why I will always even leave annoying pics in the gallery, except if you lead people that are important like your boss to this page to show them your skills or something... Then I would clean up the gallery to make an impression as good as possible
But for da-people I find, that it is really nice to see how things change during time - and within the folders, you always see the newest deviations, so... yeah
Leave it if you ask me