You need more practice---If unclipping is still a problem---Practice falling---Or landing might be more appropriate.

Stay seated in the saddle, unclip well before you need to and pull that foot away from the pedal. As you come to a stop- slide forward off the saddle and put the unclipped foot down on the ground. Won't take long before you get used to the Co-ordination to get it right but watch out. Fatal thing to do is unclip left and lean right. That hurts.