Why Can't You Drop unwanted Portkeys

RosieNu

I'm sure this has probably come up before but why oh why do you have to keep the PK you pick up. Surely there must be away to allow you to ditch ones you don't want/need and get new ones. On occasions I can't tell the colour or it's not clear which is on the map and I get stuck with one I didn't want. This is especially annoying at event times. Can you not change this please Niantic??